Electronic device and driving method thereof

ABSTRACT

To provide an electronic device capable of a variety of display. To provide an electronic device capable of being operated in a variety of ways. An electronic device includes a display device and first to third surfaces. The first surface includes a region in contact with the second surface, the second surface includes a region in contact with the third surface, and the first surface includes a region opposite to the third surface. The display device includes first to third display regions. The first display region includes a region overlapping with the first surface, the second display region includes a region overlapping with the second surface, and the third display region includes a region overlapping with the third surface. The first display region has a larger area than the third display region.

TECHNICAL FIELD

One embodiment of the present invention relates to a display devicecapable of display on a curved surface. Another embodiment of thepresent invention relates to a display device capable of display ondifferent surfaces. Another embodiment of the present invention relatesto an electronic device, a light-emitting device, or a lighting devicewhich includes a display device capable of display on a curved surface,or a manufacturing method thereof. Another embodiment of the presentinvention relates to an electronic device, a light-emitting device, or alighting device which is capable of display on different surfaces, or amanufacturing method thereof.

Note that one embodiment of the present invention is not limited to theabove technical field. The technical field of one embodiment of theinvention disclosed in this specification and the like relates to anobject, a method, or a manufacturing method. In addition, one embodimentof the present invention relates to a process, a machine, manufacture,or a composition of matter. Specifically, examples of the technicalfield of one embodiment of the present invention disclosed in thisspecification include a semiconductor device, a display device, alight-emitting device, a liquid crystal display device, a power storagedevice, a memory device, a method for driving any of them, and a methodfor manufacturing any of them.

BACKGROUND ART

Recent display devices are expected to be applied to a variety of usesand become diversified. For example, a reduction in thickness,improvement in performance, and multi-functionalization of a portableinformation terminal such as a smartphone or a tablet terminal includinga touch panel have progressed.

Patent Document 1 discloses a flexible active matrix light-emittingdevice in which an organic EL element and a transistor serving as aswitching element are provided over a film substrate.

REFERENCE Patent Document

-   [Patent Document 1] Japanese Published Patent Application No,    2003-174153

DISCLOSURE OF INVENTION

An object of one embodiment of the present invention is to provide anovel electronic device. Another object of one embodiment of the presentinvention is to provide an electronic device capable of a variety ofdisplay. Another object of one embodiment of the present invention is toprovide an electronic device which can be operated in a variety of ways.Another object of one embodiment of the present invention is to providea display device (display panel) which can be used for such anelectronic device. Another object of one embodiment of the presentinvention is to provide a novel display device or the like.

Another object of one embodiment of the present invention is to providean electronic device or the like by which an appropriate image can beshot. Another object of one embodiment of the present invention is toprovide an electronic device or the like which can emit light to anobject. Another object of one embodiment of the present invention is toprovide an electronic device or the like in which a battery can beeasily replaced. Another object of one embodiment of the presentinvention is to provide an electronic device or the like which can beeasily operated. Another object of one embodiment of the presentinvention is to provide an electronic device or the like by which ashooting condition can be checked by an object of shooting. Anotherobject of one embodiment of the present invention is to provide anelectronic device or the like which can easily perform wirelesscommunication. Another object of one embodiment of the present inventionis to provide an electronic device or the like which can produce a goodquality sound. Another object of one embodiment of the present inventionis to provide an electronic device or the like which can be bent oropened.

Note that the descriptions of these objects do not preclude theexistence of other objects. Note that in one embodiment of the presentinvention, there is no need to achieve all the objects. Objects otherthan the above objects will be apparent from and can be derived from thedescription of the specification and the like.

One embodiment of the present invention is an electronic deviceincluding a display device and first to third surfaces. The firstsurface includes a region in contact with the second surface. The secondsurface includes a region in contact with the third surface. The firstsurface includes a region opposite to the third surface. The displaydevice includes first to third display regions. The first display regionincludes a region overlapping with the first surface. The second displayregion includes a region overlapping with the second surface. The thirddisplay region includes a region overlapping with the third surface. Thefirst display region has a larger area than the third display region.

Another embodiment of the present invention is an electronic deviceincluding a display device, an input device, and first to thirdsurfaces. The first surface includes a region in contact with the secondsurface. The second surface includes a region in contact with the thirdsurface. The first surface includes a region opposite to the thirdsurface. The display device includes first to third display regions. Thefirst display region includes a region overlapping with the firstsurface. The second display region includes a region overlapping withthe second surface. The third display region includes a regionoverlapping with the third surface. The input device includes a regionoverlapping with the first display region, a region overlapping with thesecond display region, and a region overlapping with the third displayregion. The first display region has a larger area than the thirddisplay region.

Another embodiment of the present invention is an electronic deviceincluding a display device and first to third surfaces. The firstsurface includes a region in contact with the second surface. The secondsurface includes a region in contact with the third surface. The firstsurface includes a region opposite to the third surface. The displaydevice includes first to third display regions. The first display regionincludes a region overlapping with the first surface. The second displayregion includes a region overlapping with the second surface. The thirddisplay region includes a region overlapping with the third surface. Thedisplay device functions as a touch sensor in the first to third displayregions. The first display region has a larger area than the thirddisplay region.

Another embodiment of the present invention is an electronic deviceincluding a display device, an image sensor, and first to thirdsurfaces. The first surface includes a region in contact with the secondsurface. The second surface includes a region in contact with the thirdsurface. The first surface includes a region opposite to the thirdsurface. The display device includes first to third display regions. Thefirst display region includes a region overlapping with the firstsurface. The second display region includes a region overlapping withthe second surface. The third display region includes a regionoverlapping with the third surface. The display device has a function ofdisplaying a first image obtained by the image sensor in the firstdisplay region. The display device has a function of displaying a secondimage obtained by the image sensor in the second display region.

Another embodiment of the present invention is the electronic devicewhich has the above structure and in which the second surface is a sidesurface.

Another embodiment of the present invention is a method for driving anelectronic device including a display device, an image sensor, and firstto third surfaces. The first surface includes a region in contact withthe second surface. The second surface includes a region in contact withthe third surface. The first surface includes a region opposite to thethird surface. The display device includes first to third displayregions. The first display region includes a region overlapping with thefirst surface. The second display region includes a region overlappingwith the second surface. The third display region includes a regionoverlapping with the third surface. The method for driving theelectronic device includes displaying a first image obtained by theimage sensor in the first display region and displaying a second imageobtained by the image sensor in the second display region.

Another embodiment of the present invention is the method for drivingthe electronic device having the above structure in which the secondsurface is a side surface.

Note that in this specification, the display device might include any ofthe following modules in its category: a module in which a connectorsuch as a flexible printed circuit (FPC) or a tape carrier package (TCP)is attached to a display panel (display device); a module having a TCPprovided with a printed wiring board at the end thereof; and a modulehaving an integrated circuit (IC) directly mounted by a chip on glass(COG) method over a substrate over which a display element is formed.

According to one embodiment of the present invention, a novel electronicdevice can be provided. According to one embodiment of the presentinvention, an electronic device capable of a variety of display can beprovided. According to one embodiment of the present invention, anelectronic device which can be operated in a variety of ways can beprovided. According to one embodiment of the present invention, adisplay device (display panel) which can be used for such an electronicdevice can be provided. According to one embodiment of the presentinvention, a novel display device or the like can be provided.

According to one embodiment of the present invention, an electronicdevice or the like by which an appropriate image can be shot can beprovided. According to one embodiment of the present invention, anelectronic device or the like which can emit light to an object can beprovided. According to one embodiment of the present invention, anelectronic device or the like in which a battery can be easily replacedcan be provided. According to one embodiment of the present invention,an electronic device or the like which can be operated can be provided.According to one embodiment of the present invention, an electronicdevice or the like by which a shooting condition can be checked by anobject of shooting can be provided. According to one embodiment of thepresent invention, an electronic device or the like which can easilyperform wireless communication can be provided. According to oneembodiment of the present invention, an electronic device or the likewhich can produce a good quality sound can be provided. According to oneembodiment of the present invention, an electronic device or the likewhich can be bent or opened can be provided.

Note that the description of these effects does not disturb theexistence of other effects. One embodiment of the present invention doesnot necessarily achieve all the objects listed above. Other effects willbe apparent from and can be derived from the description of thespecification, the drawings, the claims, and the like.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIGS. 1A1, 1A2, 1B1, and 1B2 illustrate structure examples of anelectronic device of an embodiment:

FIGS. 2A1, 2A2, 2B1, and 2B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 3A1, 3A2, 3B1, and 3B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 4A1, 4A2, 4B1, and 4B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 5A to 5C illustrate structure examples of an electronic device ofan embodiment;

FIGS. 6A to 6C illustrate structure examples of an electronic device ofan embodiment;

FIGS. 7A and 7B illustrate a structure example of an electronic deviceof an embodiment;

FIGS. 8A1, 8A2, 8B1, and 8B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 9A1, 9A2, 9B1, and 9B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 10A1, 10A2, 10B1, and 10B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 11A1, 11A2, 11B1, and 11B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 12A1 and 12A2 illustrate a structure example of an electronicdevice of an embodiment;

FIGS. 13A1, 13A2, and 13B illustrate a structure example of anelectronic device of an embodiment;

FIGS. 14A1, 14A2, and 14B illustrate a structure example of anelectronic device of an embodiment;

FIGS. 15A and 15B illustrate structure examples of an electronic deviceof an embodiment;

FIGS. 16A1, 16A2, 16B1, and 16B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 17A1 and 17A2 illustrate a structure example of an electronicdevice of an embodiment;

FIGS. 18A1, 18A2, 18B1, and 18B2 illustrate structure examples of anelectronic device of an embodiment;

FIGS. 19A1, 19A2, 19B1, and 19B2 illustrate structure examples of anelectronic device of an embodiment;

FIG. 20 illustrates a structure example of an electronic device of anembodiment;

FIG. 21 illustrates a structure example of an electronic device of anembodiment;

FIG. 22 illustrates a structure example of an electronic device of anembodiment;

FIGS. 23A to 23C illustrate a structure example of an electronic deviceof an embodiment;

FIGS. 24A to 24E illustrate a structure example of an electronic deviceof an embodiment;

FIGS. 25A to 25C illustrate a structure example of an electronic deviceof an embodiment;

FIGS. 26A to 26D illustrate structure examples of an electronic deviceof an embodiment;

FIGS. 27A to 27C illustrate structure examples of an electronic deviceof an embodiment;

FIGS. 28A to 28C illustrate a structure example of a light-emittingpanel of an embodiment;

FIGS. 29A to 29C illustrate structure examples of a light-emitting panelof an embodiment;

FIGS. 30A to 30C illustrate structure examples of a light-emitting panelof an embodiment;

FIGS. 31A to 31C are cross-sectional TEM images and a local Fouriertransform image of an oxide semiconductor;

FIGS. 32A and 32B show nanobeam electron diffraction patterns of oxidesemiconductor films and FIGS. 32C and 32D illustrate an example of atransmission electron diffraction measurement apparatus; and

FIG. 33A shows an example of structural analysis by transmissionelectron diffraction measurement and FIGS. 33B and 33C show plan-viewTEM images.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments are described below with reference to drawings. However, theembodiments can be implemented with various modes. It will be readilyappreciated by those skilled in the art that modes and details can bechanged in various ways without departing from the spirit and scope ofthe present invention. Therefore, the present invention should not beinterpreted as being limited to description of the embodiments. Notethat in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. Furthermore, the same hatching pattern isapplied to portions having similar functions, and the portions are notespecially denoted by reference numerals in some cases.

Note that a content (or may be part of the content) described in oneembodiment may be applied to, combined with, or replaced with adifferent content (or may be part of the different content) described inthe embodiment and/or a content (or may be part of the content)described in another embodiment or other embodiments.

Note that in each embodiment, content is described with reference to avariety of figures or to text described in this specification.

Note that by combining a figure (or maybe part of the figure)illustrated in one embodiment with another part of the figure, adifferent figure (or may be part of the different figure) illustrated inthe embodiment, and/or a figure (or may be part of the figure)illustrated in another embodiment or other embodiments, much morefigures can be formed.

Note that in each drawing described in this specification, the size, thelayer thickness, or the region of each component is exaggerated forclarity in some cases. Therefore, embodiments of the present inventionare not limited to such a scale.

Note that in this specification and the like, ordinal numbers such as“first”, “second”, and the like are used in order to avoid confusionamong components and do not limit the number.

Embodiment 1

In this embodiment, an electronic device of one embodiment of thepresent invention and a display device (also referred to as a displaypanel) that can be used in the electronic device are described withreference to drawings.

[Examples of Electronic Device]

FIG. 1A1 is a schematic perspective view illustrating the front surfaceside of an electronic device described below, and FIG. 1A2 is aschematic perspective view illustrating the rear surface side thereof.

The electronic device illustrated in FIGS. 1A1 and 1A2 includes ahousing 101 and a display panel 110 provided on a surface (e.g., a frontsurface, a rear surface, or a side surface) of the housing 101 toperform display. Note that a cover, a resin, or the like is providedover the display panel 110 to prevent a damage and destruction in somecases.

The housing 101 has a front surface, a rear surface, a first sidesurface, a second side surface including a region in contact with thefirst side surface, a third side surface including a region opposite tothe first side surface, and a fourth side surface including a regionopposite to the second side surface. Alternatively, the housing 101 hasa first side surface. The first side surface includes a region incontact with a front surface and/or a rear surface. Alternatively, thehousing 101 has a second side surface. The second side surface includesa region in contact with a front surface and/or a rear surface.Alternatively, the housing 101 has a third side surface. The third sidesurface includes a region in contact with a front surface and/or a rearsurface. Alternatively, the housing 101 has a fourth side surface. Thefourth side surface includes a region in contact with a front surfaceand/or a rear surface.

Note that the front surface includes a region opposite to the rearsurface.

In other words, the housing 101 has a plurality of surfaces. Forexample, the housing 101 has a front surface, a rear surface, and atleast four side surfaces. Each surface might smoothly change; thus, theboundary between surfaces is not easily determined in some cases.Description is made using “side surface”, and the side surface includesa region of part of a front surface or a rear surface in sonic cases.

For example, the side surface refers to a region which can be observedfrom the side (for example, the direction in which the rear surface orthe front surface cannot be seen). Note that in the case where the frontsurface, the rear surface, the side surface, or the like has a curvedsurface, it is difficult to determine the boundary in some cases. Inthis case, for example, it can be said in some cases that one region ispart of the front surface (rear surface) and part of the side surface.Similarly, for example, it can be said in some cases that one region ispart of one side surface and part of another side surface.

For example, the side surface includes a region in contact with thefront surface. Alternatively, the side surface includes a region incontact with the rear surface. For example, the side surface includes aregion in contact with another side surface.

Here, the front surface and/or the rear surface includes a flat region,for example. Alternatively, the front surface and/or the rear surfaceincludes a curved region, for example. The side surface includes acurved region, for example. Alternatively, the side surface includes aflat region, for example. Note that it is difficult to distinguish thefront surface and the rear surface in some cases. Therefore, the frontsurface is referred to as a rear surface, or the rear surface isreferred to as a front surface in some cases. Note that the frontsurface includes a larger display region than the rear surface in somecases. Note that the area of the side surface is smaller than that ofthe front surface or the rear surface, for example.

Note that another surface may be provided in addition to the abovesurfaces. In other words, the housing 101 is not a hexagon but has alarger number of surfaces in some cases. Alternatively, the housing 101has a smaller number of surfaces than the above in some cases.

The display panel 110 includes a display region 111 provided to includea region overlapping with the front surface of the housing 101. Thedisplay panel 110 includes a display region 113 provided to include aregion overlapping with one of the side surfaces of the housing 101. Thedisplay panel 110 includes a display region 116 provided to include aregion overlapping with a region of part of the rear surface of thehousing 101. Note that here, a side of a side surface on which thedisplay region 113 is provided is shorter than a side of a side surfaceon which the display region 113 is not provided, for example. The areaof a side surface on which the display region 113 is provided is smallerthan that of a side surface on which the display region 113 is notprovided, for example. In other words, a side surface on which thedisplay region 113 is provided is parallel to the minor-axis directionand perpendicular to the major-axis direction, for example.

The boundaries of the display region 111, the display region 113, andthe display region 116 are denoted by dotted lines in drawings in somecases. Note that the boundaries can be different from those denoted bydotted lines in drawings depending on circumstances or conditions.

In the four side surfaces of the housing 101, a region including aregion overlapping with at least the display panel 110 preferably has acurved surface. For example, it is preferable that there be no cornerportion between the front surface and the side surface and between theside surface and the rear surface and that these surfaces be continuous.A side surface is preferably a curved surface such that the inclinationof a tangent line is continuous from the front surface to the rearsurface of the housing 101, for example. In particular, the side surfaceis preferably a developable surface that is obtained by transforming aflat surface without expansion and contraction. With such a shape, thedisplay panel 110 can be smoothly bent. In other words, the curvatureradius when the display panel 110 is bent can be increased. Thus, thedisplay panel 110 can be hardly affected by bending, and the lifetime ofthe display panel 110 can be increased. Furthermore, with such a shape,an image displayed on the display panel 110 can be seen to be smoothlychanged. Therefore, the image can be viewed with less unpleasantsensation. Note that one embodiment of the present invention is notlimited to the above examples.

Here, for example, the area of the display region 111 is larger thanthat of the display region 116. For example, the length of a side of thedisplay region 111 is longer than that of a side of the display region116. Therefore, as illustrated in FIGS. 1B1 and 1B2, a region 201 can beobtained on the rear surface of the housing 101. In other words, thedisplay region 116 and the region 201 are provided on the rear surfaceof the housing 101. For example, the display region 116 is not providedin the region 201. Thus, components having a variety of functions can beprovided in the region 201.

For example, the area of the display region 116 is greater than or equalto 10% and less than or equal to 90% of the area of the display region111. Preferably, the area of the display region 116 is, for example,greater than or equal to 30% and less than or equal to 70% of the areaof the display region 111,

For example, the length of a side of the display region 116 is greaterthan or equal to 10% and less than or equal to 90% of the length of aside of the display region 111. Preferably, the length of a side of thedisplay region 116 is, for example, greater than or equal to 30% andless than or equal to 70% of the length of a side of the display region111.

Note that on a surface of the housing 101 (e.g., a front surface, a rearsurface, or a side surface), a hardware button, an external connectionterminal, an image sensor, an infrared ray sensor, a microphone, aspeaker, or the like may he provided in addition to the display panel110.

Although FIGS. 1A1 and 1A2 show the case where one side surface of thehousing 101 is used as the display region, the display region may beoverlapped with another side surface.

For example, FIGS. 2A1 and 2A2 show a structure example where a displayregion 115 is further provided. The display region 115 includes a regionoverlapping with a side surface opposite to the display region 113.Here, FIG. 2A1 is a schematic perspective view illustrating the frontsurface side of an electronic device, and FIG. 2A2 is a schematicperspective view illustrating the rear surface side thereof. FIGS. 2B1and 2B2 show the case where the region 201 is provided.

As another example, FIGS. 3A1 and 3A2 show a structure example where thedisplay panel 110 includes the display region 111, the display region116, and a display region 112. Here, the display region 112 is providedto include a region overlapping with one of the side surfaces of thehousing 101. Here, the length of a side of the side surface on which thedisplay region 112 is provided is longer than that of a side of the sidesurface on which the display region 112 is not provided (e.g., the sidesurface on which the display region 113 is provided in FIG. 1A1). Forexample, the area of the side surface on which the display region 112 isprovided is larger than that of the side surface on which the displayregion 112 is not provided. In other words, the side surface on whichthe display region 112 is provided is parallel to the major-axisdirection and perpendicular to the minor-axis direction, for example.Here, FIG. 3A1 is a schematic perspective view illustrating the frontsurface side of the electronic device, and FIG. 3A2 is a schematicperspective view illustrating the rear surface side thereof FIGS. 3B1and 3B2 show the case where the region 201 is provided.

Furthermore, as another example, FIGS. 4A1 and 4A2 show a structureexample of the case where a display region 114 including a regionoverlapping with the side surface opposite to the display region 112 isfurther provided. Here, FIG. 441 is a schematic perspective viewillustrating the front surface side of an electronic device, and FIG.4A2 is a schematic perspective view illustrating the rear surface sidethereof. FIGS. 4B1 and 4B2 show the case where the region 201 isprovided.

As another example, FIGS. 5A to 5C show structure examples where thedisplay panel 110 includes the display region 111, the display region116, the display region 112, and the display region 113. Here, thedisplay region 112 is provided to include a region overlapping with oneof the side surfaces of the housing 101. The display region 113 isprovided to include a region overlapping with another one of the sidesurfaces of the housing 101. Here, the length of a side of the sidesurface on which the display region 112 is provided is longer than thatof a side of the side surface on which the display region 113 isprovided, for example. The area of the side surface on which the displayregion 112 is provided is larger than that of the side surface on whichthe display region 113 is provided, for example. Here, FIG. 5A shows anexample of a schematic perspective view illustrating the front surfaceside of an electronic device, and FIG. 5B shows an example of aschematic perspective illustrating the rear surface side thereof. FIG.5C shows an example different from that in FIG. 5B. FIGS. 6A to 6C showthe case where the region 201 is provided.

With such a structure, display can be performed not only on a surfaceparallel to a front surface of a housing but also on a side surface anda rear surface of the housing. In particular, a display region ispreferably provided along two or more side surfaces of the housingbecause the variations of display are further increased.

The display region 111 provided along the front surface of the housing101, the display region 116 provided along the rear surface of thehousing 101, and the display regions provided along the side surfaces ofthe housing 101 may be independently used as display regions to displaydifferent images and the like, or two or more of the display regions maydisplay one image or the like. For example, a continuous image may bedisplayed on the display region III provided along the front surface ofthe housing 101, the display region 112 provided along the side surfaceof the housing 101, the display region 116 provided along the rearsurface of the housing 101, and the like.

For example, text data, a plurality of icons associated with anapplication or the like, and the like may be displayed on the displayregion 111 provided along the front surface of the housing 101. Iconsassociated with an application or the like, and the like may bedisplayed on the display region 112.

Furthermore, display can be performed so that text data or the likerolls (moves) across a plurality of display regions (e.g., the displayregion 113 and the display region 112) provided along the side surfacesof the housing 101. Alternatively, display can be performed so that textdata or the like rolls (moves) across display regions along the frontsurface, the side surface, and the rear surface. By performing displayacross two or more surfaces of the housing in this manner, a user can beprevented from missing displayed data regardless of the direction of theelectronic device when, for example, a phone call is received.

In addition, transmitter information (e.g., a name, a phone number, ane-mail address, and the like of a transmitter) may be displayed on notonly the display region 111 but also the display region 116, a displayregion provided along the side surface such as the display region 112,and the like when, for example, a phone call or a text message isreceived. For example, transmitter information may be displayed to flowin the display region 112 and the display region 113 when a text messageis received.

FIGS. 7A and 7B show an example of a use state of an electronic device.In FIG. 7A, a plurality of icons 121 are displayed on the display region111 and a slide bar 125 is displayed on the display region 112. Bytouching the slide bar 125 with a finger 126 or the like to move theslide bar up or down, display contents such as the icons 121 displayedon the display region 111 are slid up or down accordingly as illustratedin FIG. 7B. FIGS. 7A and 7B illustrate a state where images of theplurality of icons 121 and the like are slid up from the display region111 to the display region 113 by sliding the slide bar 125 down with thefinger 126.

Although the case where an image displayed on the display region 111 isan icon is shown here, one embodiment of the present invention is notlimited thereto; depending on a launched application, a variety of datasuch as text, still images, and moving images can be displayed bysliding the slide bar 125 with a finger or the like. The position of theslide bar 125 is not limited to the display region 112, and the slidebar 125 may be provided on the display region 111, the display region113, the display region 114, the display region 116, or the like.

During a standby time during which the electronic device is not used,display on the display region 111 provided along the front surface ofthe housing 101 and/or display on the display region 116 provided alongthe rear surface thereof may be turned off (e.g., black display), datamay be displayed only on the display region 112 or the like providedalong the side surface, and the display state may be switched. Displayon the display region 111 or the display region 116 which has an arealarger than those of the other display regions is not performed, so thatpower consumption in a standby time can be reduced. Alternatively, incontrast, only display on the display region 111 is performed anddisplay on at least one of regions such as the display region 116 and aside surface display region is not performed, so that power consumptionin use can be reduced.

Alternatively, display of data may be performed in only part of thedisplay region 111 provided along the front surface of the housing 101,the display region 116 provided along the rear surface of the housing101, the display region 112 provided along the side surface of thehousing 101, and the like. For example, display may be performed in thedisplay region 111 and the display region 116, and display of thedisplay region 112 provided along the side surface, or the like may heturned off.

Furthermore, it is preferable that an input device such as a touchsensor be included at a position overlapping with the display panel 110,specifically, in regions overlapping with display regions. As a touchsensor, for example, a sheet-like capacitive touch sensor may beprovided to overlap with the display panel 110. Alternatively, aso-called in-cell touch sensor in which the display panel 110 itself hasa touch sensor function may be used. In this case, it can be said thatthe display panel 110 has not only a display function hut also afunction as a touch sensor. As an in-cell touch panel, a capacitivetouch sensor may be used or an optical touch sensor using aphotoelectric conversion element may be used. Alternatively, a so-calledon-cell touch sensor having a touch sensor function on a countersubstrate of the display panel 110 (a substrate over which a transistoror the like is not provided) may be used. Also in this case, it can besaid that the display panel 110 has not only a display function but alsoa touch sensor function. Alternatively, a so-called cover integratedtouch panel in which a cover or a cover glass which is provided on anoutermost surface of the housing 101 and prevents damage and the likehas a touch sensor function may be used. Alternatively, a touch sensorin which an optical film included in the display panel 110 has a touchsensor function may be used.

It is desirable that an input device such as a touch sensor is providedin the entire region where the display panel 110 can perform display,for example. Note that one embodiment of the present invention is notlimited thereto. For example, in part or the whole of each of thedisplay region 111, the display region 112, the display region 113, thedisplay region 114, the display region 115, and the display region 116may include a region where an input device such as a touch sensor is notprovided. For example, part or the whole of the display region 116 mayinclude a region where an input device such as a touch sensor is notprovided. Alternatively, a region of part or the whole of the displayregion 112 and a region of part or the whole of the display region 114may include a region where an input device such as a touch sensor is notprovided. By providing such a region where a touch sensor is notprovided, a malfunction can be prevented. Furthermore, an electronicdevice can be easily handled.

For example, combination of touch operations on the display region 111,the display region 112, the display region 113, the display region 114,the display region 115, or the display region 116 is preferablyassociated with an application operation.

An example of association between combination of touch operations on thedisplay region 112, the display region 113, and the display region 115and an application operation is shown. For example, a power on/offoperation is performed when all the three display regions are touched.When the display region 112 and the display region 114 are touched atthe same time, an application associated with text messages is startedand contents of a text message are displayed at the same time. When thedisplay region 112 and the display region 113 are touched at the sametime, application for making a phone call is started. When the displayregion 113 and the display region 114 are touched at the same time, aweb browser is started.

The above association between the touch operation and the application isan example, and it is preferable that a developer of operating system orapplication software or a user can determine an association asappropriate.

When, in a state where the display region 111 is touched, any one ormore of the other display regions are touched, application operationsare performed, in which case an unintended operation can be less likelyto be started.

By associating combination of touch operations on a plurality of regionswith application operations as described above, an intuitive operationis possible; thus, a user-friendly human interface can be obtained.

An electronic device of one embodiment of the present invention canperform display along not only the front surface but also one or moreside surfaces of the housing and display can also be performed on therear surface of the housing; thus, display can be performed in variousways as compared with a conventional electronic device. Furthermore, atouch sensor is provided in each of the display regions; thus, variousoperations can be performed as compared with a conventional electronicdevice and an electronic device capable of a more intuitive operationcan be obtained.

Note that an example of the case where a variety of display is performedusing the display panel 110 is shown here; however, one embodiment ofthe present invention is not limited thereto. For example, depending oncircumstances or conditions, data is not necessarily displayed in oneembodiment of the present invention. As an example, in one embodiment ofthe present invention, the electronic device may be used as a lightingdevice, not the display panel 110. In one embodiment of the presentinvention, by using the device as a lighting device, it can be used asinterior lighting having an attractive design. Alternatively, in oneembodiment of the present invention, it can be used as lighting withwhich various directions can be illuminated. Further alternatively, inone embodiment of the present invention, it may be used as a lightsource, e.g., a backlight or a front light, not the display panel 110.In other words, in one embodiment of the present invention, it may beused as a lighting device for the display panel.

Although an example where the one or two of the side surfaces of thehousing 101 are used as the display region is shown, one embodiment ofthe present invention is not limited thereto. FIGS. 8A1 and 8A2 show anexample. Here, FIG. 8A1 shows an example of a schematic perspective viewillustrating the front surface side of an electronic device and FIG. 8A2shows an example of a schematic perspective view illustrating the rearsurface side thereof. Similarly, FIGS. 8B1 and 8B2 show an example ofschematic perspective views illustrating the front surface side and therear surface side of an electronic device. FIGS. 9A1 and 9A2 show anexample of schematic perspective views illustrating the front surfaceside and the rear surface side of an electronic device. FIGS. 9B1 and9B2 show an example of schematic perspective views illustrating thefront surface side and the rear surface side of an electronic device.

In these cases, the region 201 may be provided similarly. As an exampleof this case, FIGS. 10AI and 10A2 show an example of schematicperspective views illustrating the front surface side and the rearsurface side of an electronic device. FIGS. 10B1 and I0B2 show anexample of schematic perspective views illustrating the front surfaceside and the rear surface side of an electronic device. FIGS. 11A1 and11A2 show an example of schematic perspective views illustrating thefront surface side and the rear surface side of an electronic device.FIGS. 11B1 and 11B2 show an example of schematic perspective viewsillustrating the front surface side and the rear surface side of anelectronic device.

Although this embodiment shows an example where one display panel 110includes a plurality of display regions, one embodiment of the presentinvention is not limited thereto. Each display region may be formedusing a plurality of display panels. For example, the display region 111and the display region 116 may be formed using different display panels.FIGS. 12A1 and 12A2 show an example of this case. Here, FIG. 12A1 is aschematic perspective view illustrating the front surface side of anelectronic device, and FIG. 12A2 is a schematic perspective viewillustrating the rear surface side thereof.

This embodiment shows an example of a basic principle. Thus, part or thewhole of this embodiment can be freely combined with, applied to, orreplaced with part or the whole of another embodiment.

Embodiment 2

In this embodiment, an example where an image sensor is provided in theregion 201 is shown. Here, an example where an image sensor is providedin the region 201 in FIGS. 1B1 and 1B2 is shown. Note that oneembodiment of the present invention is not limited thereto. In a varietyof drawings, e.g., FIGS. 2B1 and 2B2, a variety of elements or the likecan be provided in the region 201 similarly.

First, FIG. 13A1 is a schematic perspective view illustrating the frontsurface side of an electronic device, and FIG. 13A2 is a schematicperspective view illustrating the rear surface side thereof. An imagesensor 202 is provided in the region 201. The image sensor 202 has afunction of shooting a still image. That is, the image sensor 202 has afunction of a camera. Therefore, the image sensor 202 includes a varietyof optical components such as a lens in some cases.

As illustrated in FIG. 13B, by setting the image sensor 202 to face anobject 205, a still image, a moving image, or the like can be shot. Atthis time, an image 206 of the object 205 is displayed on the displayregion 111, for example. On the display region 111, a state of theobject 205 can be displayed in real time. While the image 206 ischecked, a still image or a moving image of the object 205 is shot. Atthis time, in the case where the illuminance of the object 205 is low,an image 204 for lighting is displayed on the display region 116, forexample. Light is emitted to the object 205 from a region on which theimage 204 for lighting is displayed. As a result, the illuminance of theobject 205 can be increased. Thus, an appropriate clear image can beshot.

The image 204 for lighting is desirably a white image, for example. Notethat one embodiment of the present invention is not limited thereto. Bychanging the display color of the image 204 for lighting, the color oflight emitted to the object 205 can be changed. Accordingly, images ofthe object 205 in a variety of states can be shot. For example, in thecase where ambient environment light is reddish, bluish, or greenish, orthe like, the image 204 for lighting is changed to an appropriate color;thus, an appropriate image can be shot.

By changing the display color of the image 204 for lighting, an image ofthe object 205 may be shot a plurality of times. For example, images areshot with the display of the image 204 for lighting being white,incandescent color, and daylight white. Then, by processing theseimages, an appropriate image can be obtained.

The image 204 for lighting desirably has the same color or gray scale onthe entire surface, for example. Note that one embodiment of the presentinvention is not limited thereto. A plurality of regions may beprovided, and images with respective different colors may be used forthe regions.

Next, as another example, FIGS. 14A1 and 14A2 show an example where theimage sensor 202 and a lighting element 203 are provided in the region201.

Here, FIG. 14A1 is a schematic perspective view illustrating the frontsurface side of an electronic device and FIG. 14A2 is a schematicperspective view illustrating the rear surface side thereof. Asillustrated in FIG. 14B, by setting the image sensor 202 and thelighting element 203 to face the object 205, a still image, a movingimage, or the like can be shot. At this time, the image 206 of theobject 205 is displayed on the display region 111, for example. On thedisplay region 111, a state of the object 205 can be displayed in realtime. While the image 206 is checked, a still image or a moving image ofthe object 205 is shot. At this time, an image 207 of the object 205 isalso displayed on the display region 116, for example. As a result, theobject 205 can check how an image thereof is shot, while seeing theimage 207. Thus, an image can be shot at an appropriate angle.

The image 206 and the image 207 are displayed on different displayregions. Therefore, they are different in the size, resolution, or thelike in some cases. It can be said that the image 206 and the image 207are different images. Note that the image 206 and the image 207 may havethe same size and the same resolution.

In the case where the illuminance of the object 205 is low, light isemitted to the object 205 from the lighting element 203. As a result,the illuminance of the object 205 can be increased. Thus, an appropriateclear image can be shot.

The lighting element 203 desirably emits white light, for example. Notethat one embodiment of the present invention is not limited thereto. Bychanging the emission color of the lighting element 203, the color oflight emitted to the object 205 can be changed. Accordingly, images ofthe object 205 in a variety of states can be shot. For example, in thecase where ambient environment light is reddish, bluish, or greenish, orthe like, the emission color of the lighting element 203 is changed toan appropriate color; thus, an appropriate image can be shot.

By changing the emission color of the lighting element 203, an image ofthe object 205 may be shot a plurality of times. For example, images areshot with the emission color of the lighting element 203 being white,incandescent color, and daylight white. Then, by processing theseimages, an appropriate image can be obtained.

The lighting element 203 desirably has the same color or gray scale, forexample. Note that one embodiment of the present invention is notlimited thereto. A plurality of lighting elements 203 emitting light ofdifferent colors may be provided.

Although the image 207 is displayed in FIG. 14A2, the image 204 forlighting may be displayed as illustrated in FIG. 15A or, depending oncircumstances, not the image 207 but the image 204 for lighting may bedisplayed as illustrated in FIG. 15B. By utilizing light from the image204 for lighting and light from the lighting element 203, theilluminance can be increased or the color of illumination light can bechanged. In other words, the lighting element 203 and the image 204 forlighting can be used as a plurality of lighting elements.

Although an example where the display region 111 and the display region116 are used is shown here, one embodiment of the present invention isnot limited thereto. Another display region may he used.

For example, an icon 208 may be displayed on the display region 113. Anexample of this case is shown in FIGS. 16A1 and 16A2. FIG. 16A1 is aschematic perspective view illustrating the front surface side of anelectronic device and FIG. 16A2 is a schematic perspective viewillustrating the rear surface side thereof. A similar example is shownin FIGS. 16B1 and 16B2. FIG. 16B1 is a schematic perspective viewillustrating the front surface side of an electronic device and FIG.16B2 is a schematic perspective view illustrating the rear surface sidethereof.

The icon 208 has a function as a shutter button, for example. An imagecan be shot by touching the icon 208. Alternatively, the focus can beadjusted by touching the icon 208.

Although the icon 208 has a function as a shutter button here, oneembodiment of the present invention is not limited thereto. By providingdedicated hardware, e.g., a shutter button, a shutter function may beobtained.

For example, an icon 209 may be displayed on the display region 112.FIGS. 17A1 and 17A2 show an example of this case. FIG. 17A1 is aperspective schematic view illustrating the front surface side of anelectronic device and FIG. 17A2 is a perspective schematic viewillustrating the rear surface side thereof.

Here, the icon 209 has a function as a slider, for example. By moving aslider, an image can be enlarged or reduced at the time of shooting. Inother words, a zoom function can be controlled. In this case, enlargingor reducing an image may be controlled optically by controlling a lensof the image sensor 202 or by controlling a digital image by software.Therefore, before an image is shot, the magnification can be controlledby moving the bar of the icon 209.

Although a zoom function is obtained by using the icon 209 here, oneembodiment of the present invention is not limited thereto. By providingdedicated hardware, e.g., an operation button, a zoom function may beobtained.

Note that the icon 208 and the icon 209 may be displayed on the samedisplay region (e.g., the display region 112). Furthermore, a variety oficons, characters, images, or the like can be displayed on displayregions.

In the case where the region 201 is provided, the image sensor 202 orthe lighting element 203 can be provided in the large region. Therefore,for example, a large lens can be provided in the image sensor 202.Alternatively, the image sensor 202 having a large size can be provided.Thus, a clear and high-resolution image can be shot.

Although an example where the image sensor 202 and the lighting element203 are provided in the region 201 is shown here, one embodiment of thepresent invention is not limited thereto. For example, the image sensor202 or the lighting element 203 may be provided in a region other thanthe region 201. FIGS. 18A1 and 18A2 show an example of this case. FIG.18A1 is a schematic perspective view illustrating the front surface sideof an electronic device and FIG. 18A2 is a schematic perspective viewillustrating the rear surface side thereof. Similarly, FIGS. 18B1 and18B2 show another example. FIG. 18B1 is a schematic perspective viewillustrating the front surface side of an electronic device and FIG.18B2 is a schematic perspective view illustrating the rear surface sidethereof.

A plurality of image sensors 202 may be provided. At least one of theimage sensors 202 may be provided in the region 201. Alternatively, allof the image sensors 202 may be provided in a region other than theregion 201.

Note that the example in which the region 201 is provided is shown;however, one embodiment of the present invention is not limited to thisexample. Depending on circumstances or conditions, the region 201 is notnecessarily provided. In this case, the area of the display region 111is substantially equal to that of the display region 116, for example.FIGS. 19A1 and 19A2 show an example of this case. FIG. 19A1 is aschematic perspective view illustrating the front surface side of anelectronic device and FIG. 19A2 is a schematic perspective viewillustrating the rear surface side thereof. Similarly, FIGS. 19B1 and19B2 show another example. FIG. 19B1 is a schematic perspective viewillustrating the front surface side of an electronic device and FIG.19B2 is a schematic perspective view illustrating the rear surface sidethereof.

Such a shooting operation may be performed when software which achievesa camera function is carried out or as part of software which achievesanother function. For example, the shooting operation may be performedwhen software which achieves a videophone function is carried out.

These functions can be achieved by software or hardware. In the case ofsoftware, it may be installed from a computer to the electronic deviceor it may be installed to the electronic device through a wired orwireless telecommunication line. Alternatively, software may beinitially stored in a memory device included in the electronic device.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

Embodiment 3

This embodiment shows an example where a variety of components areprovided in the region 201. Although an example where a variety ofcomponents are provided in the region 201 in FIGS. 1B1 and 1B2 is shownhere, one embodiment of the present invention is not limited thereto. Ina variety of different drawings, e.g., FIGS. 2B1 and 2B2, a variety ofelements or the like can be provided in the region 201 similarly. Thecomponents described in Embodiment 2 may be provided in the region 201or the like.

First, as an example, FIG. 20 shows an example where a battery 401 isprovided in the region 201. FIG. 20 is a schematic perspective viewillustrating the rear surface side of the electronic device. FIG. 20illustrates a state where a lid is opened and the battery 401 is removedfrom the housing 101. In the case where the battery 401 is put insidethe housing 101, the battery 401 can be covered with the lid so that thebattery 401 is not dropped. By providing the battery 401 in the region201 as described above, the battery 401 can be easily replaced.

Although the battery 401 can be removed in FIG. 20, one embodiment ofthe present invention is not limited thereto. Depending on circumstancesor conditions, the lid is not necessarily provided and the battery 401may be unremovable. In that case, the battery 401 can have a largethickness because the battery 401 is provided in the region 201 where adisplay region is not provided. Thus, the capacitance of the battery 401can be increased.

Next, as another example, FIG. 21 shows an example where a receivingunit 402 is provided in the region 201. As the receiving unit 402, anantenna, a coil, an electrode, or the like can be used. FIG. 21 is aschematic perspective view illustrating the rear surface side of anelectronic device. FIG. 21 illustrates a state Where the receiving unit402 is provided inside the housing 101 and communicates with acommunication device 403 wirelessly. For example, the receiving unit 402can be used as an antenna for near field communication (NFC). With NFC,a function of electronic money, a credit card, or the like can beachieved. In this case, the region 201 is provided not to overlap withthe display region 116. For example, a touch sensor also is not providedin the region 201. Thus, a radio wave, magnetism, an electromagneticwave, and the like are not disturbed by a touch sensor, a display panel,or the like, and the receiving unit 402 can be efficiently used.

The receiving unit 402 may have a transmitting function, not a receivingfunction. Alternatively, the receiving unit 402 may have both of atransmitting function and a receiving function. For example, thereceiving unit 402 is not limited as long as it can communicate data,energy, and the like.

The receiving unit 402 can be used for a variety of purposes, e.g., TV,phone, Bluetooth, short-distance communication, or the like in additionto NFC. Furthermore, the receiving unit 402 can be used as a unit forcharging an electronic device. For example, with a coil, an antenna, orthe like, an electronic device can be charged wirelessly.

Next, as another example, FIG. 22 shows an example where a speaker 404and a speaker 405 are provided in the region 201. FIG. 22 is a schematicperspective view illustrating the rear surface side of an electronicdevice. FIG. 22 illustrates a state where the speaker 404 and thespeaker 405 are provided in the housing 101. As an example, the speaker404 can emit sound for the left ear and the speaker 405 can emit soundfor the right ear. The speaker 404 and the speaker 405 can be providedto be apart from each other in the region 201. Thus, a stereophonicsound can be produced.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

Embodiment 4

In this embodiment, examples where a display panel (a display device) anelectronic device can be used by being bent or folded in a variety ofways are shown. Description is made with reference to FIGS. 23A to 23C.

FIG. 23A illustrates an electronic device 150 of a mode in which thedisplay panel 110 is developed (first mode). FIG. 23C illustrates theelectronic device 150 of a mode in which the display panel 110 is folded(second mode). FIG. 23B illustrates the electronic device 150 of a modein which the display panel 110 is bent. In other words, FIG. 23Billustrates the electronic device 150 in the middle of changing from oneof the mode in which the display panel 110 is developed (first mode) andthe mode in which the display panel 110 is folded (second mode) to theother. In FIGS. 23B and 23C, the display panel 110 is bent so that theoutside thereof is seen. Note that one embodiment of the presentinvention is not limited thereto. The display panel 110 may be bent sothat the inside thereof is hidden.

The electronic device 150 illustrated in FIGS. 23A to 23C includes thedisplay panel 110 having flexibility. The electronic device 150 furtherincludes a plurality of support panels 153 a, a plurality of supportpanels 155 a, and a plurality of support panels 155 b.

The support panel 153 a is formed using, for example, a material havinglower flexibility than that of the display panel 110 (i.e., a materialharder to bend). Furthermore, the support panel 155 a and the supportpanel 155 b are formed using, for example, a material having lowerflexibility than that of the support panel 153 a (i.e., a materialharder to bend). As illustrated in FIGS. 23A to 23C, the support panelsare preferably arranged in the periphery of the display panel 110 and ona surface opposite to a display portion of the display panel 110 becausethe display panel 110 has increased mechanical strength and becomes lesslikely to be broken.

Moreover, when the support panels 153 a, 155 a, and 155 b are preferablyformed with a material having a light-blocking property, irradiation ofdriver circuit portions of the display panel 110 with external light canbe suppressed. Accordingly, light deterioration of transistors and thelike used in the driver circuit portions can be suppressed.

Although not illustrated in FIGS. 23A to 23C, an arithmetic portion, amemory portion, a sensor portion, and the like of the electronic device150 can be arranged between the display panel 110 and the support panels155 b.

The support panels 153 a, 155 a, and 155 b can be formed using plastic,a metal, an alloy, rubber, or the like as a material. Plastic, rubber,or the like is preferably used because it can form a support panel thatis lightweight and less likely to be broken. For example, siliconerubber, stainless steel, or aluminum may be used as the support panels153 a, 155 a, and 155 b.

Furthermore, the display panel 110 including the display portion havingflexibility in the electronic device 150 can be folded either inward oroutward. When the electronic device 150 is not used, the display panel110 is folded to be inside, whereby scratches and stains on the displaypanel 110 can be suppressed.

Here, for example, as illustrated in FIG. 23A, the region 201 isprovided in the vicinity of the display panel 110. Therefore, forexample, as in another embodiment, the display region 111 has a largerarea than the display region 116. In the region 201, a variety ofcomponents can be provided as in another embodiment.

Here, FIGS. 24A and 24B illustrate a state where the display panel isfolded as illustrated in FIG. 23C. FIG. 24A shows an example of thefront surface and FIG. 24B shows an example of the rear surface. Forexample, the image sensor 202 or the lighting element 203 may beprovided in the region 201. In the display region 111, for example, theimage 206 is displayed. In the display region 116, for example, theimage 207 is displayed. FIG. 24C shows the case Where the icon 208 andthe icon 209 are displayed on the display region 112, for example. Asillustrated in FIGS. 24C to 24E, by moving a slider, a zoom functionsuch as enlargement and reduction can be controlled.

Although FIGS. 23A to 23C illustrate the case where the region 201 isprovided, one embodiment of the present invention is not limitedthereto. For example, FIGS. 25A to 25C illustrate the case where theregion 201 is not provided. Similarly, FIGS. 26A and 26B illustrate astate where the display panel is folded. The state illustrated in FIG.26B may be replaced with the state illustrated in FIG. 26C or FIG. 26D.

Although FIGS. 23A to 23C illustrate the case where the number of foldsis one, one embodiment of the present invention is not limited thereto.A plurality of folds may be provided. For example, FIG. 27A shows anexample where three folds are provided. For example, FIG. 27B shows anexample where four folds are provided. Also in these cases, the region201 is not necessarily provided. An example of this case is shown inFIG. 27C.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

Embodiment 5

In this embodiment, a structure of a touch panel that can be used in anelectronic device of one embodiment of the present invention will bedescribed with reference to FIGS. 28A to 28C.

FIG. 28A is a front view illustrating a structure of a touch panel thatcan be used in an electronic device of one embodiment of the presentinvention.

FIG. 28B is a cross-sectional view taken along line A-B and line C-D inFIG. 28A.

FIG. 28C is a cross-sectional view taken along line E-F in FIG. 28A.

<Front Surface View>

A touch panel 300 described as an example in this embodiment includes adisplay portion 301 (see FIG. 28A).

The display portion 301 includes a plurality of pixels 302 and aplurality of imaging pixels 308. The imaging pixels 308 can sense atouch of a finger or the like on the display portion 301. Thus, a touchsensor can be formed using the imaging pixels 308.

Each of the pixels 302 includes a plurality of sub-pixels (e.g., asub-pixel 302R). In addition, in the sub-pixels, light-emitting elementsand pixel circuits that can supply electric power for driving thelight-emitting elements are provided.

The pixel circuits are electrically connected to wirings through whichselection signals are supplied and wirings through which image signalsare supplied.

Furthermore, the touch panel 300 is provided with a scan line drivercircuit 303 g(1) that can supply selection signals to the pixels 302 andan image signal line driver circuit 303 s(1) that can supply imagesignals to the pixels 302.

The imaging pixels 308 include photoelectric conversion elements andimaging pixel circuits that drive the photoelectric conversion elements.

The imaging pixel circuits are electrically connected to wirings throughwhich control signals are supplied and wirings through which powersupply potentials are supplied.

Examples of the control signals include a signal for selecting animaging pixel circuit from which a recorded imaging signal is read, asignal for initializing an imaging pixel circuit, and a signal fordetermining the time it takes for an imaging pixel circuit to detectlight.

The touch panel 300 is provided with an imaging pixel driver circuit 303g(2) that can supply control signals to the imaging pixels 308 and animaging signal line driver circuit 303 s(2) that reads out imagingsignals.

<Cross-Sectional View>

The touch panel 300 includes a substrate 310 and a counter substrate 370that faces the substrate 310 (see FIG. 28B).

The substrate 310 is a stacked body in which a flexible substrate 310 b,a barrier film 310 a that prevents diffusion of unintentional impuritiesto the light-emitting elements, and an adhesive layer 310 c thatattaches the barrier film 310 a to the substrate 310 b are stacked.

The counter substrate 370 is a stacked body including a flexiblesubstrate 370 b, a barrier film 370 a that prevents diffusion ofunintentional impurities to the light-emitting elements, and an adhesivelayer 370 c that attaches the barrier film 370 a to the substrate 370 b(see FIG. 28B).

A sealant 360 attaches the counter substrate 370 to the substrate 310.The sealant 360 also serving as an optical adhesive layer has arefractive index higher than that of air. The pixel circuits and thelight-emitting elements (e.g., a light-emitting element 350R) areprovided between the substrate 310 and the counter substrate 370.

<<Structure of Pixel>>

Each of the pixels 302 includes the sub-pixel 302R, a sub-pixel 302G,and a sub-pixel 302B (see FIG. 28C). The sub-pixel 302R includes alight-emitting module 380R, the sub-pixel 302G includes a light-emittingmodule 380G, and the sub-pixel 302B includes a light-emitting module380B.

For example, the sub-pixel 302R includes the light-emitting element 350Rand the pixel circuit that can supply electric power to thelight-emitting element 350R and includes a transistor 302 t (see FIG.28B). Furthermore, the light-emitting module 380R includes thelight-emitting element 350R and an optical element (e.g., a coloringlayer 367R).

The light-emitting element 350R includes a lower electrode 351R, anupper electrode 352, and a layer 353 containing a light-emitting organiccompound between the lower electrode 351R and the upper electrode 352(see FIG. 28C).

The layer 353 containing a light-emitting organic compound includes alight-emitting unit 353 a, a light-emitting unit 353 b, and anintermediate layer 354 between the light-emitting units 353 a and 353 b.

The light-emitting module 380R includes the coloring layer 367R on thecounter substrate 370. The coloring layer transmits light of aparticular wavelength and is, for example, a layer that selectivelytransmits light of red, green, or blue color. Note that a region thattransmits light emitted from the light-emitting element as it is may heprovided as well.

The light-emitting module 380R, for example, includes the sealant 360that is in contact with the light-emitting element 350R and the coloringlayer 367R.

The coloring layer 367R is positioned in a region overlapping with thelight-emitting element 350R. Accordingly, part of light emitted from thelight-emitting element 350R passes through the sealant 360 that alsoserves as an optical adhesive layer and through the coloring layer 367Rand is emitted to the outside of the light-emitting module 380R asindicated by arrows in FIGS. 28B and 28C.

Note that although the case where the light-emitting element is used asa display element is described here, one embodiment of the presentinvention is not limited thereto.

For example, in this specification and the like, a display element, adisplay device which is a device including a display element, alight-emitting element, and a light-emitting device which is a deviceincluding a light-emitting element can employ a variety of modes or caninclude a variety of elements. Examples of a display element, a displaydevice, a light-emitting element, or a light-emitting device include anEL (electroluminescent) element (e.g., an EL element including organicand inorganic materials, an organic EL element, or an inorganic ELelement), an LED (e.g., a white LED, a red LED, a green LED, or a blueLED), a transistor (a transistor which emits light depending oncurrent), an electron emitter, a liquid crystal element, electronic ink,an electrophoretic element, a grating light valve (GLV), a plasmadisplay panel (PDP), a display element using a micro electro mechanicalsystem (MEMS), a digital micromirror device (DMD), a digital microshutter (DMS), MIRASOL (registered trademark), an interferometricmodulator display (IMOD) element, a MEMS shutter display element, anoptical interference type MEMS display element, an electrowettingelement, a piezoelectric ceramic display, or a carbon nanotube, whichare display media whose contrast, luminance, reflectivity,transmittance, or the like is changed by electromagnetic action.Examples of display devices having EL elements include an EL display.Examples of a display device including an electron emitter include afield emission display (FED), and an SED-type flat panel display (SED:surface-conduction electron-emitter display). Examples of displaydevices including liquid crystal elements include a liquid crystaldisplay (e.g., a transmissive liquid crystal display, a transflectiveliquid crystal display, a reflective liquid crystal display, adirect-view liquid crystal display, or a projection liquid crystaldisplay). Display devices having electronic ink or electrophoreticelements include electronic paper and the like. In the case of atransflective liquid crystal display or a reflective liquid crystaldisplay, some of or all of pixel electrodes function as reflectiveelectrodes. For example, some or all of pixel electrodes are formed tocontain aluminum, silver, or the like. In such a case, a memory circuitsuch as an SRAM can be provided under the reflective electrodes, leadingto lower power consumption.

<<Structure of Touch Panel>>

The touch panel 300 includes a light-blocking layer 367BM on the countersubstrate 370. The light-blocking layer 367BM is provided so as tosurround the coloring layer the coloring layer 367R).

The touch panel 300 includes an anti-reflective layer 367 p positionedin a region overlapping with the display portion 301. As theanti-reflective layer 367 p, a circular polarizing plate can be used,for example.

The touch panel 300 includes an insulating film 321. The insulating film321 covers the transistor 302 t. Note that the insulating film 321 canbe used as a layer for planarizing unevenness caused by the pixelcircuits. An insulating film on which a layer that can prevent diffusionof impurities to the transistor 302 t and the like is stacked can beused as the insulating film 321.

The touch panel 300 includes the light-emitting elements (e.g., thelight-emitting element 350R) over the insulating film 321.

The touch panel 300 includes, over the insulating film 321, a partition328 that overlaps with an end portion of the lower electrode 351R (seeFIG. 28C). In addition, a spacer 329 that controls the distance betweenthe substrate 310 and the counter substrate 370 is provided on thepartition 328.

<<Structure of Image Signal Line Driver Circuit>>

The image signal line driver circuit 303 s(1) includes a transistor 303t and a capacitor 303 c. Note that the driver circuit can be formed inthe same process and over the same substrate as those of the pixelcircuits. As illustrated in FIG. 28B, the transistor 303 t may include asecond gate over the insulating film 321. The second gate may beelectrically connected to a gate of the transistor 303 t, or differentpotentials may be supplied thereto. The second gate may be provided in atransistor 308 t described below, the transistor 302 t, or the like ifnecessary.

<<Structure of Imaging Pixel>>

The imaging pixels 308 each include a photoelectric conversion element308 p and an imaging pixel circuit for sensing light received by thephotoelectric conversion element 308 p. The imaging pixel circuitincludes the transistor 308 t.

For example, a PIN photodiode can be used as the photoelectricconversion element 308 p.

<<Other Structures>>

The touch panel 300 includes a wiring 311 through which a signal can besupplied. The wiring 311 is provided with a terminal 319. Note that anFPC 309(1) through which a signal such as an image signal or asynchronization signal can be supplied is electrically connected to theterminal 319.

Note that a printed wiring board (PWB) may be attached to the FPC309(1).

Transistors formed in the same process can be used as the transistor 302t, the transistor 303 t, the transistor 308 t, and the like.

Transistors of a bottom-gate type, a top-gate type, or the like can beused.

As a gate, source, and drain of a transistor, and a wiring or anelectrode included in a touch panel, a single-layer structure or astacked structure using any of metals such as aluminum, titanium,chromium, nickel, copper, yttrium, zirconium, molybdenum, silver,tantalum, and tungsten, or an alloy containing any of these metals asits main component can be used. For example, a single-layer structure ofan aluminum film containing silicon, a two-layer structure in which analuminum film is stacked over a titanium film, a two-layer structure inwhich an aluminum film is stacked over a tungsten film, a two-layerstructure in which a copper film is stacked over acopper-magnesium-aluminum alloy film, a two-layer structure in which acopper film is stacked over a titanium film, a two-layer structure inwhich a copper film is stacked over a tungsten film, a three-layerstructure in which a titanium film or a titanium nitride film, analuminum film or a copper film, and a titanium film or a titaniumnitride film are stacked in this order, and a three-layer structure inwhich a molybdenum film or a molybdenum nitride film, an aluminum filmor a copper film, and a molybdenum film or a molybdenum nitride film arestacked in this order can be given. Note that a transparent conductivematerial containing indium oxide, tin oxide, or zinc oxide may be used.Copper containing manganese is preferably used because controllabilityof a shape by etching is increased.

For example, silicon is preferably used as a semiconductor in which achannel of a transistor such as the transistor 302 t, the transistor 303t, or the transistor 308 t is formed. Although amorphous silicon may beused as silicon, silicon having crystallinity is particularlypreferable. For example, microcrystalline silicon, polycrystallinesilicon, single crystal silicon, or the like is preferably used. Inparticular, polycrystalline silicon can be formed at a lower temperaturethan single crystal silicon and has higher field effect mobility andhigher reliability than amorphous silicon. When such a polycrystallinesemiconductor is used for a pixel, the aperture ratio of the pixel canbe improved. Even in the case where pixels are included at extremelyhigh resolution, a gate driver circuit and a source driver circuit canbe formed over a substrate over which the pixels are formed, the numberof components included in an electronic device can be reduced.

Here, an oxide semiconductor is preferably used for semiconductordevices such as transistors used for pixels included in display regionsor driver circuits in the display panel 110. In particular, an oxidesemiconductor having a wider band gap than silicon is preferably used. Asemiconductor material having a wider band gap and a lower carrierdensity than silicon is preferably used because off-state current of thetransistor can be reduced.

The oxide semiconductor preferably contains at least indium (In) or zinc(Zn), for example. More preferably, the oxide semiconductor contains anoxide represented by an In-M-Zn-based oxide (M is a metal such as Al,Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

As the semiconductor layer, it is particularly preferable to use anoxide semiconductor film including a plurality of crystal parts whosec-axes are aligned perpendicular to a surface on which the semiconductorlayer is formed or the top surface of the semiconductor layer and inwhich the adjacent crystal parts have no grain boundary.

There is no grain boundary in such an oxide semiconductor; therefore,generation of a crack in an oxide semiconductor film which is caused bystress when a display panel is bent is prevented. Therefore, such anoxide semiconductor can be preferably used for a flexible display panelwhich is used in a bent state, or the like.

The use of such materials for the semiconductor layer makes it possibleto provide a highly reliable transistor in which a change in theelectrical characteristics is suppressed.

Charge accumulated in a capacitor through a transistor can be held for along time because of the low off-state current of the transistor. Whensuch a transistor is used for a pixel, operation of a driver circuit canbe stopped while a gray scale of an image displayed on each displayregion is maintained. As a result, an electronic device with anextremely low power consumption can be obtained.

Note that details of a preferable mode and a formation method of anoxide semiconductor that can be used for the semiconductor layer aredescribed in an embodiment below.

Here, a method for forming a flexible light-emitting panel is described.

Here, a structure including a pixel and a driver circuit or a structureincluding an optical member such as a color filter is referred to as anelement layer for convenience. An element layer includes a displayelement, for example, and may include a wiring electrically connected toa display element or an element such as a transistor used in a pixel ora circuit in addition to the display element.

Here, a support provided with an insulating surface over which anelement layer is formed is called a base material.

As a method for forming an element layer over a base material providedwith an insulating surface having flexibility, there are a method inwhich the element layer is formed directly over the base material, and amethod in which the element layer is formed over a supporting basematerial having stiffness unlike the base material, and then the elementlayer is separated from the supporting base material and transferred tothe base material.

In the case where a material of the base material can withstand heatingtemperature in the process for forming the element layer, it ispreferable that the element layer be formed directly over the basematerial, in which case a manufacturing process can be simplified. Atthis time, the element layer is preferably formed in a state where thebase material is fixed to the supporting base material, in which casetransfer of the element layer in a device and between devices can beeasy.

In the case of employing the method in which the element layer is formedover the supporting base material and then transferred to the basematerial, first, a separation layer and an insulating layer are stackedover a supporting base material, and then the element layer is formedover the insulating layer. Then, the element layer is separated from thesupporting base material and then transferred to the base material. Atthis time, a material is selected so that separation at an interfacebetween the supporting base material and the separation layer, at aninterface between the separation layer and the insulating layer, or inthe separation layer occurs.

For example, it is preferable that a stacked layer of a layer includinga high-melting-point metal material, such as tungsten, and a layerincluding an oxide of the metal material be used as the separationlayer, and a stacked layer of a plurality of layers, such as a siliconnitride layer and a silicon oxynitride layer be used over the separationlayer. The use of the high-melting-point metal material is preferablebecause the degree of freedom of the process for forming the elementlayer can be increased.

The separation may be performed by application of mechanical power, byetching of the separation layer, by dripping of a liquid into part ofthe separation interface to penetrate the entire separation interface,or the like. Alternatively, separation may be performed by heating theseparation interface by utilizing a difference in coefficient of thermalexpansion.

The peeling layer is not necessarily provided in the case where peelingcan occur at an interface between the supporting base material and theinsulating layer. For example, glass may be used as the supporting basematerial, an organic resin such as polyimide may be used as theinsulating layer, a separation trigger may be formed by locally heatingpart of the organic resin by laser light or the like, and peeling may beperformed at an interface between the glass and the insulating layer.Alternatively, a metal layer may be provided between the supporting basematerial and the insulating layer formed of an organic resin, andseparation may be performed at the interface between the metal layer andthe insulating layer by heating the metal layer by feeding a current tothe metal layer. In that case, the insulating layer formed of an organicresin can be used as a base material.

Examples of such a base material having flexibility include polyesterresins such as polyethylene terephthalate (PET) and polyethylenenaphthalate (PEN), a polyacrylonitrile resin, a polyimide resin, apolymethyl methacrylate resin, a polycarbonate (PC) resin, apolyethersulfone (PES) resin, a polyamide resin, a cycloolefin resin, apolystyrene resin, a polyamide imide resin, and a polyvinyl chlorideresin. In particular, a material whose thermal expansion coefficient islow, for example, lower than or equal to 30×10⁻⁶ /K is preferable, and apolyamide imide resin, a polyimide resin, or PET can be suitably used. Asubstrate in which a fibrous body is impregnated with a resin (alsoreferred to as prepreg) or a substrate whose thermal expansioncoefficient is reduced by mixing an inorganic filler with an organicresin can also be used.

In the case where a fibrous body is included in the above material, ahigh-strength fiber of an organic compound or an inorganic compound isused as the fibrous body. The high-strength fiber is specifically afiber with a high tensile modulus of elasticity or a fiber with a highYoung's modulus. Typical examples thereof include a polyvinyl alcoholbased fiber, a polyester based fiber, a polyamide based fiber, apolyethylene based fiber, an aramid based fiber, a polyparaphenylenebenzobisoxazole fiber, a glass fiber, and a carbon fiber. As the glassfiber, glass fiber using E glass, S glass, D glass, Q glass, or the likecan be used. These fibers may be used in a state of a woven fabric or anonwoven fabric, and a structure body in which this fibrous body isimpregnated with a resin and the resin is cured may be used as theflexible substrate. The structure body including the fibrous body andthe resin is preferably used as the flexible substrate, in which casethe reliability against bending or breaking due to local pressure can beincreased.

Note that for a display device of one embodiment of the presentinvention, an active matrix method in which an active element isincluded in a pixel or a passive matrix method in which an activeelement is not included in a pixel can be used,

In an active matrix method, as an active element (a non-linear element),not only a transistor but also various active elements (non-linearelements) can be used. For example, a metal insulator metal (MIM), athin film diode (TFD), or the like can also be used. Since such anelement has a small number of manufacturing steps, manufacturing costcan be reduced or yield can be improved. Alternatively, since the sizeof the element is small, the aperture ratio can be improved, so thatpower consumption can be reduced or higher luminance can be achieved.

As a method other than the active matrix method, the passive matrixmethod in which an active element (a non-linear element) is not used canalso be used. Since an active element (a non-linear element) is notused, the number of manufacturing steps is small, so that manufacturingcost can be reduced or the yield can be improved. Alternatively, sincean active element (a non-linear element) is not used, the aperture ratiocan be improved, so that power consumption can be reduced or higherluminance can be achieved, for example.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

Embodiment 6

In this embodiment, a structure of a foldable touch panel that can beused in the electronic device of one embodiment of the present inventionwill be described with reference to FIGS. 29A to 29C.

FIGS. 29A to 29C are cross-sectional views of a touch panel 500.

The touch panel 500 includes a display portion 501 and a touch sensor595. Furthermore, the touch panel 500 includes a substrate 510, asubstrate 570, and a substrate 590. Note that the substrate 510, thesubstrate 570, and the substrate 590 each have flexibility.

The display portion 501 includes the substrate 510, a plurality ofpixels over the substrate 510, and a plurality of wirings 511 throughwhich signals are supplied to the pixels. The plurality of wirings 511is led to a peripheral portion of the substrate 510, and part of theplurality of wirings 511 forms a terminal 519. The terminal 519 iselectrically connected to an FPC 509(1).

<Touch Sensor>

The substrate 590 includes the touch sensor 595 and a plurality ofwirings 598 electrically connected to the touch sensor 595. Theplurality of wirings 598 is led to a peripheral portion of the substrate590, and part of the plurality of wirings 598 forms a terminal. Theterminal is electrically connected to an FPC 509(2).

As the touch sensor 595, a capacitive touch sensor can be used. Examplesof the capacitive touch sensor are a surface capacitive touch sensor anda projected capacitive touch sensor.

Examples of the projected capacitive touch sensor are a self capacitivetouch sensor and a mutual capacitive touch sensor, which differ mainlyin the driving method. The use of a mutual capacitive touch sensor ispreferable because multiple points can be sensed simultaneously.

An example of using a projected capacitive touch sensor will bedescribed below.

Note that a variety of sensors that can sense the closeness or thecontact of a sensing target, such as a finger, can be used.

The projected capacitive touch sensor 595 includes electrodes 591 andelectrodes 592. The electrodes 591 are electrically connected to any ofthe plurality of wirings 598, and the electrodes 592 are electricallyconnected to any of the other wirings 598.

A wiring 594 electrically connects two electrodes 591 between which theelectrode 592 is positioned. The intersecting area of the electrode 592and the wiring 594 is preferably as small as possible. Such a structureallows a reduction in the area of a region where the electrodes are notprovided, reducing unevenness in transmittance. As a result, unevennessin luminance of light from the touch sensor 595 can be reduced.

Note that the shapes of the electrodes 591 and the electrodes 592 can beany of a variety of shapes. For example, the plurality of electrodes 591may be provided so that a space between the electrodes 591 is reduced asmuch as possible, and a plurality of electrodes 592 may be provided withan insulating layer sandwiched between the electrodes 591 and theelectrodes 592 and may be spaced apart from each other to form a regionnot overlapping with the electrodes 591. In that case, between twoadjacent electrodes 592, it is preferable to provide a dummy electrodewhich is electrically insulated from these electrodes, whereby the areaof a region having a different transmittance can be reduced.

The touch sensor 595 includes the substrate 590, the electrodes 591 andthe electrodes 592 provided in a staggered arrangement on the substrate590, an insulating layer 593 covering the electrodes 591 and theelectrodes 592, and the wiring 594 that electrically connects theadjacent electrodes 591 to each other.

An adhesive layer 597 attaches the substrate 590 to the substrate 570 sothat the touch sensor 595 overlaps with the display portion 501.

The electrodes 591 and the electrodes 592 are formed using alight-transmitting conductive material. As the light-transmittingconductive material, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded, or graphene can be used.

The electrodes 591 and the electrodes 592 may be formed by depositing alight-transmitting conductive material on the substrate 590 by asputtering method and then removing an unnecessary portion by any ofvarious patterning techniques such as photolithography. Graphene may beformed in such a manner that a solution in which graphene oxide isdispersed is applied and reduced, in addition to a CVD method.

Examples of a material for the insulating layer 593 are a resin such asacrylic or epoxy resin, a resin having a siloxane bond, and an inorganicinsulating material such as silicon oxide, silicon oxynitride, oraluminum oxide.

Furthermore, openings reaching the electrodes 591 are formed in theinsulating layer 593, and the wiring 594 electrically connects theadjacent electrodes 591. A light-transmitting conductive material can befavorably used as the wiring 594 because the aperture ratio of the touchpanel can be increased. Moreover, a material with higher conductivitythan the conductivities of the electrodes 591 and 592 can be favorablyused as the wiring 594 because electric resistance can be reduced.

One electrode 592 extends in one direction, and a plurality ofelectrodes 592 is provided in the form of stripes.

The wiring 594 intersects with the electrode 592.

Adjacent electrodes 591 are provided with one electrode 592 providedtherebetween. The wiring 594 electrically connects the adjacentelectrodes 591.

Note that the plurality of electrodes 591 is not necessarily arranged inthe direction orthogonal to one electrode 592 and may be arranged tointersect with one electrode 592 at an angle of less than 90 degrees.

One wiring 598 is electrically connected to any of the electrodes 591and 592. Part of the wiring 598 serves as a terminal. For the wiring598, a metal material such as aluminum, gold, platinum, silver, nickel,titanium, tungsten, chromium, molybdenum, iron, cobalt, copper, orpalladium or an alloy material containing any of these metal materialscan be used.

Note that an insulating layer that covers the insulating layer 593 andthe wiring 594 may be provided to protect the touch sensor 595.

Furthermore, a connection layer 599 electrically connects the wiring 598to the FPC 509(2).

As the connection layer 599, any of anisotropic conductive films (ACF),anisotropic conductive pastes (ACP), and the like can be used.

The adhesive layer 597 has a light-transmitting properly. For example, athermosetting resin or an ultraviolet curable resin can be used;specifically, a resin such as an acrylic resin, an urethane resin, anepoxy resin, or a resin having a siloxane bond can be used.

<Display Portion>

The display portion 501 includes a plurality of pixels arranged in amatrix. Each of the pixels includes a display element and a pixelcircuit for driving the display element.

In this embodiment, an example of using an organic electroluminescentelement that emits white light as a display element will be described;however, the display element is not limited to such element. Organicelectroluminescent elements for different colors, for example, anorganic electroluminescent element for red, an organicelectroluminescent element for blue, and an organic electroluminescentelement for green may be used.

Other than organic electroluminescent elements, any of various displayelements such as display elements (electronic ink) that perform displayby an electrophoretic method, an electronic liquid powder method, or thelike; MEMS shutter display elements; and optical interference type MEMSdisplay elements can be used. A structure suitable for employed displayelements can be selected from among a variety of structures of pixelcircuits.

The substrate 510 is a stacked body in which a flexible substrate 510 b,a barrier film 510 a that prevents diffusion of unintentional impuritiesto light-emitting elements, and an adhesive layer 510 c that attachesthe barrier film 510 a to the substrate 510 b are stacked.

The substrate 570 is a stacked body in which a flexible substrate 570 b,a barrier film 570 a that prevents diffusion of unintentional impuritiesto the light-emitting elements, and an adhesive layer 570 c thatattaches the barrier film 570 a to the substrate 570 b are stacked.

A sealant 560 attaches the substrate 570 to the substrate 510. Thesealant 560 has a refractive index higher than that of air. In the caseof extracting light to the sealant 560 side, the sealant 560 serves asan optical adhesive layer. The pixel circuits and the light-emittingelements (e.g., a light-emitting element 550R) are provided between thesubstrate 510 and the substrate 570.

<<Structure of Pixel>>

A pixel includes a sub-pixel 502R, and the sub-pixel 502R includes alight-emitting module 580R.

The sub-pixel 502R includes the light-emitting element 550R and thepixel circuit that can supply electric power to the light-emittingelement 550R and includes a transistor 502 t. Furthermore, thelight-emitting module 580R includes the light-emitting element 550R andan optical element (e.g., a coloring layer 567R).

The light-emitting element 550R includes a lower electrode, an upperelectrode, and a layer containing a light-emitting organic compoundbetween the lower electrode and the upper electrode.

The light-emitting module 580R includes the coloring layer 567R on thelight extraction side. The coloring layer transmits light of aparticular wavelength and is, for example, a layer that selectivelytransmits light of red, green, or blue color. Note that in anothersub-pixel, a region that transmits light emitted from the light-emittingelement as it is may he provided as well.

In the case where the sealant 560 is provided on the light extractionside, the sealant 560 is in contact with the light-emitting element 550Rand the coloring layer 567R.

The coloring layer 567R is positioned in a region overlapping with thelight-emitting element 550R. Accordingly, part of light emitted from thelight-emitting element 550R passes through the coloring layer 567R andis emitted to the outside of the light-emitting module 580R as indicatedby an arrow in FIG. 29A.

<<Structure of Display Portion>>

The display portion 501 includes a light-blocking layer 567BM on thelight extraction side. The light-blocking layer 567BM is provided so asto surround the coloring layer (e.g., the coloring layer 567R).

The display portion 501 includes an anti-reflective layer 567 ppositioned in a region overlapping with pixels. As the anti-reflectivelayer 567 p, a circular polarizing plate can be used, for example.

The display portion 501 includes an insulating film 521. The insulatingfilm 521 covers the transistor 502 t. Nate that the insulating film 521can be used as a layer for planarizing unevenness caused by the pixelcircuits. A stacked film including a layer that can prevent diffusion ofimpurities can be used as the insulating film 521. This can prevent thereliability of the transistor 502 t or the like from being lowered bydiffusion of unintentional impurities.

The display portion 501 includes the light-emitting elements (e.g., thelight-emitting element 550R) over the insulating film 521.

The display portion 501 includes, over the insulating film 521, apartition 528 that overlaps with an end portion of a lower electrode. Inaddition, a spacer that controls the distance between the substrate 510and the substrate 570 is provided on the partition 528.

<<Structure of Scan Line Driver Circuit>>

A scan line driver circuit 503 g(1) includes a transistor 503 t and acapacitor 503 c. Note that the driver circuit can be formed in the sameprocess and over the same substrate as those of the pixel circuits.

<<Other Structures>>

The display portion 501 includes the wirings 511 through which signalscan be supplied. The wirings 511 are provided with the terminal 519.Note that the FPC 509(1) through which a signal such as an image signalor a synchronization signal can be supplied is electrically connected tothe terminal 519.

Note that a printed wiring board (PWB) may be attached to the FPC509(1).

<Modification Example 1 of Display Portion>

Any of various kinds of transistors can be used in the display portion501.

A structure in the case of using bottom-gate transistors in the displayportion 501 is illustrated in FIGS. 29A and 29B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 29A.

For example, a semiconductor layer containing polycrystalline silicon orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 29B.

A structure in the case of using top-gate transistors in the displayportion 501 is illustrated in FIG. 29C.

For example, a semiconductor layer containing polycrystalline silicon, atransferred single crystal silicon film, or the like can be used in thetransistor 502 t and the transistor 503 t illustrated in FIG. 29C.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

Embodiment 7

In this embodiment, a structure of a foldable touch panel that can beused in the electronic device of one embodiment of the present inventionwill be described with reference to FIGS. 30A to 30C.

FIGS. 30A to 30C are cross-sectional views of a touch panel 500B.

The touch panel 500B described in this embodiment is different from thetouch panel 500 described in Embodiment 6 in that the display portion501 displays received image data to the side where the transistors areprovided and that the touch sensor is provided on the substrate 510 sideof the display portion. Different structures will be described in detailbelow, and the above description is referred to for the other similarstructures.

<Display Portion>

The display portion 501 includes a plurality of pixels arranged in amatrix. Each of the pixels includes a display element and a pixelcircuit for driving the display element.

<<Structure of Pixel>>

A pixel includes the sub-pixel 502R, and the sub-pixel 502R includes alight-emitting module 580R.

The sub-pixel 502R includes the light-emitting element 550R and thepixel circuit that can supply electric power to the light-emittingelement 550R and includes the transistor 502 t.

The light-emitting module 580R includes the light-emitting element 550Rand an optical element (e.g., the coloring layer 567R).

The light-emitting element 550R includes a lower electrode, an upperelectrode, and a layer containing a light-emitting organic compoundbetween the lower electrode and the upper electrode.

The light-emitting module 550R includes the coloring layer 567R on thelight extraction side. The coloring layer transmits light of aparticular wavelength and is, for example, a layer that selectivelytransmits light of red, green, or blue color. Note that in anothersub-pixel, a region that transmits light emitted from the light-emittingelement as it is may be provided as well.

The coloring layer 567R is positioned in a region overlapping with thelight-emitting element 550R. The light-emitting element 550R illustratedin FIG. 30A emits light to the side where the transistor 502 t isprovided. Accordingly, part of light emitted from the light-emittingelement 550R passes through the coloring layer 567R and is emitted tothe outside of the light-emitting module 580R as indicated by an arrowin FIG. 30A.

<<Structure of Display Portion>>

The display portion 501 includes a light-blocking layer 567BM on thelight extraction side. The light-blocking layer 567BM is provided so asto surround the coloring layer (e.g., the coloring layer 567R).

The display portion 501 includes the insulating film 521. The insulatingfilm 521 covers the transistor 502 t. Note that the insulating film 521can be used as a layer for planarizing unevenness caused by the pixelcircuits. A stacked film including a layer that can prevent diffusion ofimpurities can be used as the insulating film 521. This can prevent thereliability of the transistor 502 t or the like from being lowered bydiffusion of unintentional impurities from the coloring layer 567R.

<Touch Sensor>

The touch sensor 595 is provided on the substrate 510 side of thedisplay portion 501 (see FIG. 30A).

The adhesive layer 597 is provided between the substrate 510 and thesubstrate 590 and attaches the touch sensor 595 to the display portion501.

<Modification Example 1 of Display Portion>

Any of various kinds of transistors can be used in the display portion501.

A structure in the case of using bottom-gate transistors in the displayportion 501 is illustrated in FIGS. 30A and 30B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 30A.

For example, a semiconductor layer containing polycrystalline silicon orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 30B.

A structure in the case of using top-gate transistors in the displayportion 501 is illustrated in FIG. 30C.

For example, a semiconductor layer containing polycrystalline silicon, atransferred single crystal silicon film, or the like can be used in thetransistor 502 t and the transistor 503 t illustrated in FIG. 30C.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

Embodiment 8

An oxide semiconductor suitable for a semiconductor layer of asemiconductor device that can be used for a display panel of oneembodiment of the present invention is described in this embodiment.

An oxide semiconductor has a wide energy gap of 3.0 eV or more. Atransistor including an oxide semiconductor film obtained by processingof the oxide semiconductor in an appropriate condition and a sufficientreduction in carrier density of the oxide semiconductor can have muchlower leakage current between a source and a drain in an off state(off-state current) than a conventional transistor including silicon.

An applicable oxide semiconductor preferably contains at least indium(In) or zinc (Zn). In particular, In and Zn are preferably contained. Inaddition, as a stabilizer for reducing variation in electricalcharacteristics of the transistor using the oxide semiconductor, one ormore selected from gallium (Ga), tin (Sn), hafnium (Hf), zirconium (Zr),titanium (Ti), scandium (Sc), yttrium (Y), and an lanthanoid (e.g.,cerium (Ce), neodymium (Nd), or gadolinium (Gd)) is preferablycontained.

As the oxide semiconductor, for example, any of the following can beused: indium oxide, tin oxide, zinc oxide, an In-Zn-based oxide, aSn-Zn-based oxide, an Al-Zn-based oxide, a Zn-Mg-based oxide, aSn-Mg-based oxide, an In-Mg-based oxide, an In-Ga-based oxide, anIn-Ga-Zn-based oxide (also referred to as IGZO), an In-Al-Zn-basedoxide, an In-Sn-Zn-based oxide, a Sn-Ga-Zn-based oxide, anAl-Ga-Zn-based oxide, a Sn-Al-Zn-based oxide, an In-Hf-Zn-based oxide,an In-Zr-Zn-based oxide, an In-Ti-Zn-based oxide, an In-Sc-Zn-basedoxide, an In-Y-Zn-based oxide, an In-La-Zn-based oxide, anIn-Ce-Zn-based oxide, an In-Pr-Zn-based oxide, an In-Nd-Zn-based oxide,an In-Sm-Zn-based oxide, an In-Eu-Zn-based oxide, an In-Gd-Zn-basedoxide, an In-Tb-Zn-based oxide, an In-Dy-Zn-based oxide, anIn-Ho-Zn-based oxide, an In-Er-Zn-based oxide, an In-Tm-Zn-based oxide,an In-Yb-Zn-based oxide, an In-Lu-Zn-based oxide, an In-Sn-Ga-Zn-basedoxide, an In-Hf-Ga-Zn-based oxide, an In-Al-Ga-Zn-based oxide, anIn-Sn-Al-Zn-based oxide, an In-Sn-Hf-Zn-based oxide, or anIn-Hf-Al-Zn-based oxide.

Here, an “In-Ga-Zn-based oxide” means an oxide containing Ga, and Zn asits main components and there is no particular limitation on the ratioof In:Ga:Zn. The In-Ga-Zn-based oxide may contain a metal element otherthan the In, Ga, and Zn.

Alternatively, a material represented by InMO₃(ZnO)_(m) (m>0 issatisfied, and m is not an integer) may be used as an oxidesemiconductor. Note that M represents one or more metal elementsselected from Ga, Fe, Mn, and Co, or the above-described element as astabilizer. Alternatively, as the oxide semiconductor, a materialexpressed by a chemical formula, In₂SnO₅(ZnO)_(n) (n>0, n is an integer)may be used.

For example, In-Ga-Zn-based oxide with an atomic ratio ofIn:Ga:Zn=1:1:1, 1:3:2, 1:3:4, 1:3:6, 3:1:2, or 2:1:3, or an oxide whosecomposition is in the neighborhood of the above compositions may beused.

Note that if the oxide semiconductor film contains a large amount ofhydrogen, the hydrogen and the oxide semiconductor are bonded to eachother, so that part of the hydrogen serves as a donor and causesgeneration of an electron that is a carrier. As a result, the thresholdvoltage of the transistor shifts in the negative direction. Therefore,it is preferable that, after formation of the oxide semiconductor film,dehydration treatment (dehydrogenation treatment) be performed to removehydrogen or moisture from the oxide semiconductor film so that the oxidesemiconductor film is highly purified to contain impurities as little aspossible.

Note that oxygen in the oxide semiconductor film is also reduced by thedehydration treatment (dehydrogenation treatment) in some cases.Therefore, it is preferable that oxygen be added to the oxidesemiconductor film to fill oxygen vacancies increased by the dehydrationtreatment (dehydrogenation treatment). In this specification and thelike, supplying oxygen to an oxide semiconductor film may be expressedas oxygen adding treatment, or treatment for making the oxygen contentof an oxide semiconductor film be in excess of that of thestoichiometric composition may be expressed as treatment for making anoxygen-excess state.

In this manner, hydrogen or moisture is removed from the oxidesemiconductor film by the dehydration treatment (dehydrogenationtreatment) and oxygen vacancies therein are filled by the oxygen addingtreatment, so that the oxide semiconductor film can be an i-type(intrinsic) oxide semiconductor film or an oxide semiconductor filmextremely close to an i-type oxide semiconductor (a substantially i-typeoxide semiconductor). Note that “substantially intrinsic” means that theoxide semiconductor film includes extremely few (close to zero) carriersderived from a donor, and the carrier concentration thereof is lowerthan or equal to 1×10¹⁷ /cm³, lower than or equal to 1×10¹⁶ /cm³, lowerthan or equal to 1×10¹⁵ /cm³, lower than or equal to 1×10¹⁴ /cm³, lowerthan or equal to 1×10¹³ /cm³, particularly preferably lower than orequal to 8×10¹¹ /cm³, still further preferably lower than or equal to1×10¹¹ /cm³, yet further preferably lower than or equal to 1×10¹⁰ /cm³,and is higher than or equal to 1×10⁻⁹ /cm³.

In this manner, the transistor including an i-type or substantiallyi-type oxide semiconductor film can have extremely favorable off-statecurrent characteristics. For example, the drain current at the time whenthe transistor including an oxide semiconductor film is in an off-stateat room temperature (25° C.) can be less than or equal to 1×10⁻¹⁸ A,preferably less than or equal to 1×10⁻²¹ A, further preferably less thanor equal to 1×10⁻²⁴ A; or at 85° C., less than or equal to 1×10⁻¹⁵ A,preferably less than or equal to 1×10⁻¹⁸ A, further preferably less thanor equal to 1×10⁻²¹ A. An off state of a transistor refers to a statewhere gate voltage is lower than the threshold voltage in an n-channeltransistor. Specifically, the transistor is in an off state when thegate voltage is lower than the threshold voltage by 1 V or more, 2 V ormore, or 3 V or more. Note that these current values are values when thevoltage between a source and a drain is, for example, 1 V, 5 V, or 10 V.

A structure of the oxide semiconductor film is described below.

An oxide semiconductor film is classified roughly into a single-crystaloxide semiconductor film and a non-single-crystal oxide semiconductorfilm. The non-single-crystal oxide semiconductor film includes any of ac-axis aligned crystalline oxide semiconductor (CAAC-OS) film, apolycrystalline oxide semiconductor film, a microcrystalline oxidesemiconductor film, an amorphous oxide semiconductor film, and the like.

First, a CAAC-OS film is described. Note that a CAAC-OS can be referredto as an oxide semiconductor including c-axis aligned nanocrystals(CANC).

The CAAC-OS film is an oxide semiconductor film including a plurality ofc-axis aligned crystal parts.

In a transmission electron microscope (TEM) image of the CAAC-OS film, aboundary between crystal parts, that is, a clear grain boundary is notobserved. Thus, in the CAAC-OS film, a reduction in electron mobilitydue to the grain boundary is less likely to occur.

According to the TEM image of the CAAC-OS film observed in a directionsubstantially parallel to a sample surface (cross-sectional TEM image),metal atoms are arranged in a layered manner in the crystal parts. Eachmetal atom layer reflects unevenness of a surface over which the CAAC-OSfilm is formed (hereinafter, such a surface is referred to as aformation surface) or a top surface of the CAAC-OS film, and is arrangedparallel to the formation surface or the top surface of the CAAC-OSfilm.

On the other hand, according to the TEM image of the CAAC-OS filmobserved in a direction substantially perpendicular to the samplesurface (plan-view TEM image), metal atoms are arranged in a triangularor hexagonal configuration in the crystal parts. However, there is noregularity of arrangement of metal atoms between different crystalparts.

FIG. 31A is a cross-sectional TEM image of a CAAC-OS film. FIG. 31B is across-sectional TEM image obtained by enlarging the image of FIG. 31A.In FIG. 31B, atomic arrangement is highlighted for easy understanding.

FIG. 31C is Fourier transform images of regions each surrounded by acircle (the diameter is approximately 4 nm) between A and O and betweenO and A′ in FIG. 31A. C-axis alignment can be observed in each region inFIG. 31C. The c-axis direction between A and O is different from thatbetween O and A′, which indicates that a grain in the region between Aand O is different from that between O and A′. In addition, between Aand O, the angle of the c-axis continuously and gradually changes from14.3°, 16.6°, to 26.4°. Similarly, between O and A′, the angle of thec-axis continuously changes from −18.3°, −17.6°, to −15.9°.

Note that in an electron diffraction pattern of the CAAC-OS film, spots(luminescent spots) having alignment are shown. For example, spots areobserved in an electron diffraction pattern (also referred to as ananobeam electron diffraction pattern) of the top surface of the CAAC-OSfilm which is obtained using an electron beam with a diameter of, forexample, larger than or equal to 1 nm and smaller than or equal to 30 nm(see FIG. 32A).

From the results of the cross-sectional TEM image and the plan TEM age,alignment is found in the crystal parts in the CAAC-OS film.

Most of the crystal parts included in the CAAC-OS film each fit into acube whose one side is less than 100 nm. Thus, there is a case where acrystal part included in the CAAC-OS film fits into a cube whose oneside is less than 10 nm, less than 5 nm, or less than 3 nm. Note thatwhen a plurality of crystal parts included in the CAAC-OS film areconnected to each other, one large crystal region is formed in somecases. For example, a crystal region with an area of larger than orequal to 2500 nm², larger than or equal to 5 μm², or larger than orequal to 1000 μm² is observed in some cases in the planar TEM image.

The CAAC-OS film is subjected to structural analysis with an X-raydiffraction (XRD) apparatus. For example, when the CAAC-OS filmincluding an InGaZnO₄ crystal is analyzed by an out-of-plane method, apeak appears frequently when the diffraction angle (2θ) is around 31°.This peak is derived from the (009) plane of the InGaZnO₄ crystal, whichindicates that crystals in the CAAC-OS film have c-axis alignment, andthat the c-axes are aligned in a direction substantially perpendicularto the formation surface or the top surface of the CAAC-OS film.

On the other hand, when the CAAC-OS film is analyzed by an in-planemethod in which an X-ray enters a sample in a direction substantiallyperpendicular to the c-axis. a peak appears frequently when 2θ is around56°. This peak is derived from the (110) plane of the InGaZnO₄ crystal.Here, analysis (ϕ scan) is performed under conditions where the sampleis rotated around a normal vector of a sample surface as an axis (ϕaxis) with 2θ fixed at around 56°. In the case where the sample is asingle crystal oxide semiconductor film of InGaZnO₄, six peaks appear.The six peaks are derived from crystal planes equivalent to the (110)plane. In contrast, in the case of a CAAC-OS film, a peak is not clearlyobserved even when ϕ scan is performed with 2θ fixed at around 56°.

According to the above results, in the CAAC-OS film having c-axisalignment, while the directions of a-axes and b-axes are differentbetween crystal parts, the c-axes are aligned in a direction parallel toa normal vector of a formation surface or a normal vector of a topsurface. Thus, each metal atom layer which is arranged in a layeredmanner and observed in the cross-sectional TEM image corresponds to aplane parallel to the a-b plane of the crystal.

Note that the crystal part is formed concurrently with deposition of theCAAC-OS film or is formed through crystallization treatment such as heattreatment. As described above, the c-axis of the crystal is aligned in adirection parallel to a normal vector of a formation surface or a normalvector of a top surface of the CAAC-OS film. Thus, for example, in thecase where the shape of the CAAC-OS film is changed by etching or thelike, the c-axis might not be necessarily parallel to a normal vector ofa formation surface or a normal vector of a top surface of the CAAC-OS

Furthermore, distribution of c-axis aligned crystal parts in the CAAC-OSfilm is not necessarily uniform. For example, in the case where crystalgrowth leading to the crystal parts of the CAAC-OS film occurs from thevicinity of the top surface of the CAAC-OS film, the proportion of thec-axis aligned crystal parts in the vicinity of the top surface ishigher than that in the vicinity of the formation surface in some cases.Furthermore, when an impurity is added to the CAAC-OS film, a region towhich the impurity is added is altered, and the proportion of the c-axisaligned crystal parts in the CAAC-OS film varies depending on regions,in some cases.

Note that when the CAAC-OS film with an InGaZnO₄ crystal is analyzed byan out-of-plane method, a peak may also be observed at 2θ of around 36°,in addition to the peak at 2θ of around 31°. The peak at 2θ of around36° indicates that a crystal having no c-axis alignment is included inpart of the CAAC-OS film. It is preferable that in the CAAC-OS film, apeak appear at 2θ of around 31° and a peak do not appear at 2θ of around36°.

The CAAC-OS film is an oxide semiconductor film having low impurityconcentration. The impurity is an element other than the main componentsof the oxide semiconductor film, such as hydrogen, carbon, silicon, or atransition metal element. In particular, an element that has higherbonding strength to oxygen than a. metal element included in the oxidesemiconductor film, such as silicon, disturbs the atomic order of theoxide semiconductor film by depriving the oxide semiconductor film ofoxygen and causes a decrease in crystallinity. Furthermore, a heavymetal such as iron or nickel, argon, carbon dioxide, or the like has alarge atomic radius (molecular radius), and thus disturbs the atomicorder of the oxide semiconductor film and causes a decrease incrystallinity when it is contained in the oxide semiconductor film. Notethat the impurity contained in the oxide semiconductor film might serveas a carrier trap or a carrier generation source.

The CAAC-OS film is an oxide semiconductor film having a low density ofdefect states. In some cases, oxygen vacancies in the oxidesemiconductor film serve as carrier traps or serve as carrier generationsources when hydrogen is captured therein.

The state in which impurity concentration is low and density of defectstates is low (the number of oxygen vacancies is small) is referred toas a “highly purified intrinsic” or “substantially highly purifiedintrinsic” state. A highly purified intrinsic or substantially highlypurified intrinsic oxide semiconductor film has few carrier generationsources, and thus can have a low carrier density. Thus, a transistorincluding the oxide semiconductor film rarely has a negative thresholdvoltage (is rarely normally on). The highly purified intrinsic orsubstantially highly purified intrinsic oxide semiconductor film has fewcarrier traps. Accordingly, the transistor including the oxidesemiconductor film has little variation in electrical characteristicsand high reliability. Electric charge trapped by the carrier traps inthe oxide semiconductor film takes a long time to be released, and mightbehave like fixed electric charge. Thus, the transistor which includesthe oxide semiconductor film having high impurity concentration and ahigh density of defect states has unstable electrical characteristics insome cases.

In an OS transistor including the CAAC-OS film, changes in electricalcharacteristics of the transistor due to irradiation with visible lightor ultraviolet light are small.

Next, a microcrystalline oxide semiconductor film is described.

In an image obtained with a TEM, crystal parts cannot be found clearlyin the microcrystalline oxide semiconductor film in some cases. In mostcases, the size of a crystal part included in the microcrystalline oxidesemiconductor film is greater than or equal to 1 nm and less than orequal to 100 nm, or greater than or equal to 1 nm and less than or equalto 10 nm. A microcrystal with a size greater than or equal to 1 nm andless than or equal to 10 nm, or a size greater than or equal to 1 nm andless than or equal to 3 nm is specifically referred to as nanocrystal(nc). An oxide semiconductor film including nanocrystal is referred toas an nc-OS (nanocrystalline oxide semiconductor) film. In an image ofthe tic-OS film obtained with a TEM, for example, a grain boundarycannot be found clearly in some cases. Note that the nc-OS can also bereferred to as an oxide semiconductor including random alignednanocrystals (RANC) or an oxide semiconductor including non-alignednanocrystals (NANC).

In the nc-OS film, a microscopic region (e.g., a region with a sizegreater than or equal to 1 nm and less than or equal to 10 nm, inparticular, a region with a size greater than or equal to 1 nm and lessthan or equal to 3 nm) has a periodic atomic order. The nc-OS film doesnot have regularity of crystal orientation between different crystalparts. Thus, the orientation of the whole film is not observed.Accordingly, in some cases, the nc-OS film cannot be distinguished froman amorphous oxide semiconductor film depending on an analysis method.For example, when the nc-OS film is subjected to structural analysis byan out-of-plane method with an XRD apparatus using an X-ray having adiameter larger than that of a crystal part, a peak that shows a crystalplane does not appear. Furthermore, a halo pattern is shown in anelectron diffraction pattern (also referred to as a selected-areaelectron diffraction pattern) of the nc-OS film obtained by using anelectron beam having a probe diameter (e.g., larger than or equal to 50nm) larger than the diameter of a crystal part. Meanwhile, spots areshown in a nanobeam electron diffraction pattern of the nc-OS filmobtained by using an electron beam having a probe diameter close to, orsmaller than the diameter of a crystal part. Furthermore, in a nanobeamelectron diffraction pattern of the nc-OS film, regions with highluminance in a circular (ring) pattern are shown in some cases. Also ina nanobeam electron diffraction pattern of the nc-OS film, a pluralityof spots are shown in a ring-like region in some cases (see FIG. 32B).

Since the nc-OS film is an oxide semiconductor film having moreregularity than the amorphous oxide semiconductor film, the nc-OS filmhas a lower density of defect states than the amorphous oxidesemiconductor film. However, there is no regularity of crystalorientation between different crystal parts in the nc-OS film; hence,the nc-OS film has a higher density of defect states than the CAAC-OS

Note that an oxide semiconductor film may be a stacked film includingtwo or more films of an amorphous oxide semiconductor film, amicrocrystalline oxide semiconductor film, and a CAAC-OS film, forexample.

In the case where the oxide semiconductor film has a plurality ofstructures, the structures can be analyzed using nanobeam electrondiffraction in some cases.

FIG. 32C illustrates a transmission electron diffraction measurementapparatus that includes an electron gun chamber 10, an optical system 12below the electron gun chamber 10, a sample chamber 14 below the opticalsystem 12, an optical system 16 below the sample chamber 14, anobservation chamber 20 below the optical system 16, a camera 18installed in the observation chamber 20, and a film chamber 22 below theobservation chamber 20. The camera 18 is provided to face the inside ofthe observation chamber 20. Note that the film chamber 22 is notnecessarily provided.

FIG. 32D illustrates an internal structure of the transmission electrondiffraction measurement apparatus illustrated in FIG. 32C. In thetransmission electron diffraction measurement apparatus, a substance 28provided in the sample chamber 14 is irradiated with electrons ejectedfrom an electron gun provided in the electron gun chamber 10 through theoptical system 12. The electrons that have passed through the substance28 enter a fluorescent plate 32 provided in the observation chamber 20through the optical system 16. On the fluorescent plate 32, a patterncorresponding to the intensity of entered electron appears, which allowsmeasurement of a transmission electron diffraction pattern.

The camera 18 is set toward the fluorescent plate 32 so that a patternon the fluorescent plate 32 can be taken. An angle formed by a straightline that passes through the center of a lens of the camera 18 and thecenter of the fluorescent plate 32 and an upper surface of thefluorescent plate 32 is, for example, 15° or more and 80° or less, 30°or more and 75° or less, or 45° or more and 70° or less. As the angle isreduced, distortion of the transmission electron diffraction patterntaken by the camera 18 becomes larger. Note that if the angle isobtained in advance, the distortion of an obtained transmission electrondiffraction pattern can be corrected. Note that the film chamber 22 maybe provided with the camera 18. For example, the camera 18 may be set inthe film chamber 22 so as to be opposite to the incident direction ofelectrons 24. In this case, a transmission electron diffraction patternwith less distortion can be taken from the rear surface of thefluorescent plate 32.

A holder for fixing the substance 28 that is a sample is provided in thesample chamber 14. The holder transmits electrons passing through thesubstance 28. The holder may have, for example, a function of moving thesubstance 28 in the direction of the X, Y, and Z axes. The movementfunction of the holder may have an accuracy of moving the substance inthe range of, for example, 1 nm to 10 nm, 5 nm to 50 nm, 10 nm to 100nm, 50 nm to 500 nm, and 100 nm to 1 μm. The range is preferablydetermined to be an optimal range for the structure of the substance 28.

A method for measuring a transmission electron diffraction pattern of asubstance by the transmission electron diffraction measurement apparatusdescribed above will be describe

For example, changes in the structure of a substance can be observed bychanging (scanning) the irradiation position of the electrons 24 thatare a nanobeam in the substance, as illustrated in FIG. 32D. At thistime, when the substance 28 is a CAAC-OS film, a diffraction patternshown in FIG. 32A can be observed. When the substance 28 is an nc-OSfilm, a diffraction pattern shown in FIG. 32B can be observed.

However, even when the substance 28 is a CAAC-OS film, a diffractionpattern that is partly similar to that of an nc-OS film is observed insome cases. Therefore, whether or not a CAAC-OS film is favorable can bedetermined by the proportion of a region where a diffraction pattern ofa CAAC-OS film is observed in a predetermined area (also referred to asproportion of CAAC). In the case of a high quality CAAC-OS film, forexample, the proportion of CAAC is higher than or equal to 50%,preferably higher than or equal to 80%, further preferably higher thanor equal to 90%, still further preferably higher than or equal to 95%.Note that a proportion of a region where a diffraction pattern differentfrom that of a CAAC-OS film is referred to as the proportion ofnon-CAAC.

For example, transmission electron diffraction patterns were obtained byscanning a top surface of a sample including a CAAC-OS film obtainedjust after deposition (represented as “as-sputtered”) and a top surfaceof a sample including a CAAC-OS subjected to heat treatment at 450° C.in an atmosphere containing oxygen. Here, the proportion of CAAC wasobtained in such a manner that diffraction patterns were observed byscanning for 60 seconds at a rate of 5 nm/second and the obtaineddiffraction patterns were converted into still images every 0.5 seconds.Note that as an electron beam, a nanobeam with a probe diameter of 1 nmwas used. The above measurement was performed on six samples. Theproportion of CAAC was calculated using the average value of the sixsamples.

FIG. 33A shows the proportion of CAAC in each sample. The proportion ofCAAC of the CAAC-OS film obtained just after the deposition was 75.7%(the proportion of non-CAAC was 24.3%). The proportion of CAAC of theCAAC-OS film subjected to the heat treatment at 450° C. was 85.3% (theproportion of non-CAAC was 14.7%). These results show that theproportion of CAAC obtained after the heat treatment at 450° C. ishigher than that obtained just after the deposition. That is, heattreatment at a high temperature (e.g., higher than or equal to 400° C.)reduces the proportion of non-CAAC (increases the proportion of CAAC).Further, the above results also indicate that even when the temperatureof the heat treatment is lower than 500° C., the CAAC-OS film can have ahigh proportion of CAAC.

Here, most of diffraction patterns different from that of a CAAC-OS filmare diffraction patterns similar to that of an nc-OS film. Furthermore,an amorphous oxide semiconductor film was not able to be observed in themeasurement region. Therefore, the above results suggest that the regionhaving a structure similar to that of an nc-OS film is rearranged by theheat treatment owing to the influence of the structure of the adjacentregion, whereby the region becomes CAAC.

FIGS. 33B and 33C are planar TEM images of the CAAC-OS film obtainedjust after the deposition and the CAAC-OS film subjected to the heattreatment at 450° C. respectively. Comparison between FIGS. 33B and 33Cshows that the CAAC-OS film subjected to the heat treatment at 450° C.has more uniform film quality. That is, the heat treatment at a hightemperature improves the film quality of the CAAC-OS film.

With such a measurement method, the structure of an oxide semiconductorfilm having a plurality of structures can be analyzed in some cases.

The CAAC-OS film is formed, for example, by the following method.

For example, the CAAC-OS film is formed by a sputtering method with apolycrystalline oxide semiconductor sputtering target.

By increasing the substrate temperature during the deposition, migrationof sputtered particles is likely to occur after the sputtered particlesreach a substrate surface. Specifically, the substrate temperatureduring the deposition is higher than or equal to 100° C. and lower thanor equal to 740° C., preferably higher than or equal to 200° C. andlower than or equal to 500° C. By increasing the substrate temperatureduring the deposition, when the flat-plate-like or pellet-like sputteredparticles reach the substrate, migration occurs on the substratesurface, so that a flat plane of the sputtered particles is attached tothe substrate. At this time, the sputtered particle is chargedpositively, whereby sputtered particles are attached to the substratewhile repelling each other, thus, the sputtered particles do not overlapwith each other randomly, and a CAAC-OS film with a uniform thicknesscan be deposited.

By reducing the amount of impurities entering the CAAC-OS film duringthe deposition, the crystal state can be prevented from being broken bythe impurities. For example, the concentration of impurities (e.g.,hydrogen, water, carbon dioxide, or nitrogen) that exist in thedeposition chamber may be reduced. Furthermore, the concentration ofimpurities in a deposition gas may be reduced. Specifically, adeposition gas whose dew point is −80° C. or lower, preferably −100° C.or lower is used.

Furthermore, it is preferable that the proportion of oxygen in thedeposition gas be increased and the power be optimized in order toreduce plasma damage at the deposition. The proportion of oxygen in thedeposition gas is higher than or equal to 30 vol %, preferably 100 vol%.

Alternatively, the CAAC-OS film is formed by the following method.

First, a first oxide semiconductor film is formed to a thickness ofgreater than or equal to 1 nm and less than 10 nm. The first oxidesemiconductor film is formed by a sputtering method. Specifically, thesubstrate temperature is set to higher than or equal to 100° C. andlower than or equal to 500° C., preferably higher than or equal to 150°C. and lower than or equal to 450° C., and the proportion of oxygen in adeposition gas is set to higher than or equal to 30 vol %, preferably100 vol %.

Next, heat treatment is performed so that the first oxide semiconductorfilm becomes a first CAAC-OS film with high crystallinity. Thetemperature of the heat treatment is higher than or equal to 350° C. andlower than or equal to 740° C., preferably higher than or equal to 450°C. and lower than or equal to 650° C. The heat treatment time is longerthan or equal to 1 minute and shorter than or equal to 24 hours,preferably longer than or equal to 6 minutes and shorter than or equalto 4 hours. The heat treatment may be performed in an inert atmosphereor an oxidation atmosphere. It is preferable to perform heat treatmentin an inert atmosphere and then perform heat treatment in an oxidationatmosphere. The heat treatment in an inert atmosphere can reduce theconcentration of impurities in the first oxide semiconductor film for ashort time. At the same time, the heat treatment in an inert atmospheremay generate oxygen vacancies in the first oxide semiconductor film insuch a case, the heat treatment in an oxidation atmosphere can reducethe oxygen vacancies. Note that the heat treatment may be performedunder a reduced pressure, such as 1000 Pa or lower, 100 Pa or lower, 10Pa or lower, or 1 Pa or lower. The heat treatment under the reducedpressure can reduce the concentration of impurities in the first oxidesemiconductor film for a shorter time.

The first oxide semiconductor film with a thickness greater than orequal to 1 nm and less than 10 nm can be easily crystallized by heattreatment as compared to the case where the first oxide semiconductorfilm has a thickness greater than or equal to 10 nm.

Next, a second oxide semiconductor film having the same composition asthe first oxide semiconductor film is formed to a thickness of greaterthan or equal to 10 nm and less than or equal to 50 nm. The second oxidesemiconductor film is formed by a sputtering method. Specifically, thesubstrate temperature is set to higher than or equal to 100° C. andlower than or equal to 500° C., preferably higher than or equal to 150°C. and lower than or equal to 450° C., and the proportion of oxygen in adeposition gas is set to higher than or equal to 30 vol %, preferably100 vol %.

Next, heat treatment is performed so that solid phase growth of thesecond oxide semiconductor film is performed using the first CAAC-OSfilm, thereby forming a second CAAC-OS film with high crystallinity. Thetemperature of the heat treatment is higher than or equal to 350° C. andlower than or equal to 740° C., preferably higher than or equal to 450°C. and lower than or equal to 650° C. The heat treatment time is longerthan or equal to 1 minute and shorter than or equal to 24 hours,preferably longer than or equal to 6 minutes and shorter than or equalto 4 hours. The heat treatment may be performed in an inert atmosphereor an oxidation atmosphere. It is preferable to perform heat treatmentin an inert atmosphere and then perform heat treatment in an oxidationatmosphere. The heat treatment in an inert atmosphere can reduce theconcentration of impurities in the second oxide semiconductor film for ashort time. At the same time, the heat treatment in an inert atmospheremay generate oxygen vacancies in the second oxide semiconductor film. Insuch a case, the heat treatment in an oxidation atmosphere can reducethe oxygen vacancies. Note that the heat treatment may be performedunder a reduced pressure, such as 1000 Pa or lower, 100 Pa or lower, 10Pa or lower, or 1 Pa or lower. The heat treatment under the reducedpressure can reduce the concentration of impurities in the second oxidesemiconductor film for a shorter time.

In the above-described manner, a CAAC-OS film with a total thickness ofgreater than or equal to 10 nm can be formed.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

Embodiment 9

In the other embodiments, a variety of examples are shown. Note that oneembodiment of the present invention is not limited to the aboveexamples.

For example, in this specification and the like, transistors with avariety of structures can be used, without limitation to a certain type.For example, a transistor including single crystal silicon or atransistor including a non-single-crystal semiconductor film typified byamorphous silicon, polycrystalline silicon, microcrystalline (alsoreferred to as microcrystal, nanocrystal, or semi-amorphous) silicon, orthe like can be used. Alternatively, a thin film transistor (TFT)obtained by thinning such a semiconductor, or the like can be used. Inthe case of using the TFT, there are various advantages. For example,since the TFT can be formed at a temperature lower than that of the caseof using single crystal silicon, manufacturing cost can be reduced and alarger manufacturing apparatus can be used. Since a larger manufacturingapparatus can be used, TFTs can be formed using a large substrate.Therefore, many display devices can be formed at the same time at lowcost. Alternatively, a substrate having low heat resistance can be usedbecause of a low manufacturing temperature. Therefore, the transistorcan be formed using a light-transmitting substrate. Alternatively,transmission of light in a display element can be controlled by usingthe transistor formed using the light-transmitting substrate.Alternatively, part of a film included in the transistor can transmitlight because the thickness of the transistor is small. Therefore, theaperture ratio can be increased.

Note that by using a catalyst (e.g., nickel) in forming polycrystallinesilicon, crystallinity can be further increased and a transistor havingexcellent electrical characteristics can be formed. Accordingly, a gatedriver circuit (a scan line driver circuit), a source driver circuit (asignal line driver circuit), and a signal processing circuit (a signalgeneration circuit, a gamma correction circuit, a DA converter circuit,or the like) can be formed using the same substrate.

Note that by using a catalyst (e.g., nickel) in forming microcrystallinesilicon, crystallinity can be further increased and a transistor havingexcellent electrical characteristics can be formed. At this time,crystallinity can be increased by just performing heat treatment withoutperforming laser irradiation. Accordingly, a gate driver circuit (a scanline driver circuit) and part of a source driver circuit (e.g., ananalog switch) can be formed over the same substrate. Note that in thecase where laser irradiation for crystallization is not performed,unevenness in crystallinity of silicon can be suppressed. Accordingly,an image with improved image quality can be displayed. Note thatpolycrystalline silicon or microcrystalline silicon can be formedwithout use of a catalyst (e.g., nickel).

Note that it is preferable that the crystallinity of silicon be improvedto polycrystal, microcrystal, or the like in the whole panel; however,the crystallinity of silicon in the present invention is not limitedthereto. The crystallinity of silicon may be improved only in part ofthe panel. A selective increase in crystallinity can be achieved byselective laser irradiation or the like. For example, only a peripheraldriver circuit region, which is a region excluding pixels, may beirradiated with laser light. Alternatively, only a region of a gatedriver circuit, a source driver circuit, or the like may be irradiatedwith laser light. Alternatively, only part of a source driver circuit(e.g., an analog switch) may be irradiated with laser light. By suchselective laser irradiation, the crystallinity of silicon only in aregion in which a circuit needs to operate at high speed can beimproved. Because a pixel region is not particularly needed to operateat high speed, even if crystallinity is not improved, the pixel circuitcan operate without problems. Thus, a region whose crystallinity isimproved is small, so that manufacturing steps can be decreased. As aresult, the throughput can be increased and the manufacturing cost canbe reduced. Alternatively, the number of manufacturing apparatusesneeded is small; thus, the manufacturing cost can be reduced.

Examples of the transistor are a transistor including a compoundsemiconductor (e.g., SiGe or GaAs) or an oxide semiconductor (e.g., ZnO,InGaZnO, indium zinc oxide (IZO), indium tin oxide (ITO), SnO, TiO,AlZnSnO (AZTO), or In—Sn—Zn—O (ITZO)) and a thin film transistorincluding a thin film of such a compound semiconductor or oxidesemiconductor. Thus, the manufacturing temperature can be low and forexample, such a transistor can be formed at room temperature.Accordingly, the transistor can be formed directly on a substrate havinglow heat resistance, such as a plastic substrate or a film substrate.Nate that such a compound semiconductor or oxide semiconductor can beused for not only a channel portion of a transistor but also for otherapplications. For example, such a compound semiconductor or oxidesemiconductor can be used for a wiring, a resistive element, a pixelelectrode, a light-transmitting electrode, or the like. Since such anelement can be formed at the same time as a transistor, the cost can bereduced.

Note that for example, a transistor formed by an ink-jet method or aprinting method can be used. Accordingly, such a transistor can beformed at room temperature, can be formed at a low vacuum, or can beformed using a large substrate. Thus, the transistor can be formedwithout using a mask (reticle), which enables the layout of thetransistor to be easily changed. Alternatively, the transistor can beformed without using a resist, leading to reductions in material costand the number of steps. Furthermore, a film can be formed only in aportion where the film is needed, a material is not wasted as comparedwith the case of employing a manufacturing method by which etching isperformed after the film is formed over the entire surface, so that thecost can be reduced.

Note that for example, a transistor including an organic semiconductoror a carbon nanotube can be used. Thus, such a transistor can be formedover a flexible substrate. A device including a transistor whichincludes an organic semiconductor or a carbon nanotube can resist animpact.

Note that transistors with a variety of different structures can beused. For example, a MOS transistor, a junction transistor, a bipolartransistor, or the like can be used. Since a MOS transistor has a smallsize, a large number of transistors can be mounted. Note that a MOStransistor and a bipolar transistor may be formed over one substrate, inwhich case reductions in power consumption and size, high-speedoperation, and the like can be achieved.

Note that in this specification and the like, for example, a transistorwith a multi-gate structure having two or more gate electrodes can beused. With the multi-gate structure, a structure where a plurality oftransistors are connected in series is provided because channel regionsare connected in series. Thus, with the multi-gate structure, the amountof off-state current can be reduced and the withstand voltage of thetransistor can be increased (reliability can be unproved).Alternatively, with the multi-gate structure, the drain-source currentdoes not change so much even if the drain-source voltage fluctuates whenthe transistor operates in a saturation region, so that a flat slope ofthe voltage-current characteristics can be obtained. By utilizing theflat slope of the voltage-current characteristics, an ideal currentsource circuit or an active load having extremely high resistance can beobtained. Accordingly, a differential circuit, a current mirror circuit,or the like having excellent properties can be obtained.

Note that, for example, a transistor with a structure where gateelectrodes are provided above and below a channel can be used. With thestructure where the gate electrodes are provided above and below thechannel, a circuit structure where a plurality of transistors areconnected in parallel is provided. Thus, a channel region is increased,so that the amount of current can be increased. When the structure wherethe gate electrodes are provided above and below the channel isemployed, a depletion layer is easily format thus, the subthresholdswing (S value) can be improved.

Note that for example, a transistor with a structure where a gateelectrode is formed above a channel region, a structure where a gateelectrode is formed below a channel region, a staggered structure, aninverted staggered structure, a structure where a channel region isdivided into a plurality of regions, a structure where channel regionsare connected in parallel or in series, or the like can be used. Atransistor with any of a variety of structures such as a planar type, aFIN-type, a TRI-GATE type, a top-gate type, a bottom-gate type, adouble-gate type (with gates above and below a channel), and the likecan be used.

Note that, for example, a transistor with a structure where a sourceelectrode or a drain electrode overlaps with a channel region (or partthereof) can be used. When the structure where the source electrode orthe drain electrode overlaps with the channel region (or part thereof)is employed, unstable operation due to electric charge accumulated inpart of the channel region can be prevented.

Note that for example, a transistor with a structure where an LDD regionis provided can be used. Provision of the LDD region enables a reductionin off-current or an increase in the withstand voltage of the transistor(an improvement in reliability). Alternatively, by providing the LDDregion, the drain current does not change so much even when thedrain-source voltage fluctuates when the transistor operates in asaturation region, so that a flat slope of the voltage-currentcharacteristics can be obtained.

For example, in this specification and the like, a variety of substratescan be used to form a transistor. The type of a substrate is not limitedto a certain type. Examples of the substrate include a semiconductorsubstrate (e.g., a single crystal substrate or a silicon substrate), anSOI substrate, a glass substrate, a quartz substrate, a plasticsubstrate, a metal substrate, a stainless steel substrate, a substrateincluding stainless steel foil, a tungsten substrate, a substrateincluding tungsten foil, a flexible substrate, an attachment film, paperincluding a fibrous material, and a base material film. Examples of aglass substrate include a barium borosilicate glass substrate, analuminoborosilicate glass substrate, and soda lime glass substrate.Examples of a flexible substrate, an attachment film, a base materialfilm, or the like are as follows: plastic typified by polyethyleneterephthalate (PET), polyethylene naphthalate (PEN), and polyethersulfone (PES); a synthetic resin such as acrylic; polypropylene;polyester; polyvinyl fluoride; polyvinyl chloride; polyamide; polyimide;aramid; epoxy; an inorganic vapor deposition film; and paper.Specifically, when a transistor is formed using a semiconductorsubstrate, a single crystal substrate, an SOI substrate, or the like, itis possible to form a transistor with few variations in characteristics,size, shape, or the like, with high current supply capability, and witha small size. By forming a circuit with the use of such a transistor,power consumption of the circuit can be reduced or the circuit can behighly integrated.

Note that a transistor may be formed using a substrate, and then, thetransistor may be transferred to another substrate. Examples of asubstrate to which a transistor is transferred include, in addition tothe above substrate over which the transistor can be formed, a papersubstrate, a cellophane substrate, an aramid film substrate, a polyimidefilm substrate, a stone substrate, a wood substrate, a cloth substrate(including a natural fiber (e.g., silk, cotton, or hemp), a syntheticfiber (e.g., nylon, polyurethane, or polyester), a regenerated fiber(e.g., acetate, cupra, rayon, or regenerated polyester), and the like),a leather substrate, and a rubber substrate. The use of such a substrateenables formation of a transistor with excellent properties, atransistor with low power consumption, or a device with high durability,high heat resistance, or a reduction in weight or thickness.

Note that all the circuits which are necessary to realize a desiredfunction can be formed using one substrate (e.g., a glass substrate, aplastic substrate, a single crystal substrate, or an SOI substrate). Inthis manner, the cost can be reduced by a reduction in the number ofcomponents or reliability can be improved by a reduction in the numberof connection points to circuit components.

Note that not all the circuits which are necessary to realize thepredetermined function are needed to be formed using one substrate. Thatis, part of the circuits which are necessary to realize thepredetermined function may be formed using a substrate and another partof the circuits which are necessary to realize the predeterminedfunction may be formed using another substrate. For example, part of thecircuits which are necessary to realize the predetermined function canbe formed using a glass substrate and another part of the circuits whichare necessary to realize the predetermined function can be formed usinga single crystal substrate (or an SOI substrate). The single crystalsubstrate over which the another part of the circuits which arenecessary to realize the predetermined function (such a substrate isalso referred to as an IC chip) can be connected to the glass substrateby COG (chip on glass), and the IC chip can be provided over the glasssubstrate. Alternatively, the IC chip can be connected to the glasssubstrate by TAB (tape automated bonding), COF (chip on film), SMT(surface mount technology), a printed circuit board, or the like. Whenpart of the circuits is formed over the same substrate as a pixelportion in this manner, the cost can be reduced by a reduction in thenumber of components or reliability can be improved by a reduction inthe number of connection points between circuit components. Inparticular, a circuit in a portion where a driving voltage is high, acircuit in a portion where a driving frequency is high, or the likeconsumes much power in many cases. In view of the above, such a circuitis formed over a substrate (e.g., a single crystal substrate) differentfrom a substrate over which a pixel portion is formed, whereby an ICchip is formed. The use of this IC chip allows prevention of an increasein power consumption.

The invention excluding content which is not specified in the drawingsand texts in this specification can be constituted. Alternatively, whenthe range of a value (e.g., the maximum and minimum values) described,the range may be freely narrowed or a value in the range may beexcluded, so that the invention can be specified by a range part ofwhich is excluded. In this manner, it is possible to specify the scopeof the present invention so that a conventional technology is excluded,for example.

As a specific example, a diagram of a circuit including a firsttransistor to a fifth transistor is illustrated. In that case, it can bespecified that the circuit does not include a sixth transistor in theinvention. It can be specified that the circuit does not include acapacitor in the invention. It can also be specified that the circuitdoes not include a sixth transistor with a particular connectionstructure in the invention. Furthermore, it can be specified that thecircuit does not include a capacitor with a particular connectionstructure in the invention. For example, it can be specified that asixth transistor whose gate is connected to a gate of the thirdtransistor is not included in the invention. For example, it can bespecified that a capacitor whose first electrode is connected to thegate of the third transistor is not included in the invention.

As another specific example, a description of a value, “a voltage ispreferably higher than or equal to 3 V and lower than or equal to 10 V”is given. In that case, for example, it can be specified that the casewhere the voltage is higher than or equal to −2 V and lower than orequal to 1 V is excluded from the invention. For example, it can bespecified that the case where the voltage is higher than or equal to 13V is excluded from the invention. Note that, for example, it can bespecified that the voltage is higher than or equal to 5 V and lower thanor equal to 8 V in the invention. For example, it can be specified thatthe voltage is approximately 9 V in the invention. For example, it canbe specified that the voltage is higher than or equal to 3 V and lowerthan or equal to 10 V but is not 9 V in the invention.

As another specific example, a description “a voltage is preferred to be10 V” is given. In that case, for example, it can be specified that thecase where the voltage is higher than or equal to −2 V and lower than orequal to 1 V is excluded from the invention. For example, it can bespecified that the case where the voltage is higher than or equal to 13V is excluded from the invention.

As another specific example, a description “a film is an insulatingfilm” is given to describe properties of a material. In that case, forexample, it can be specified that the case where the insulating film isan organic insulating film is excluded from the invention. For example,it can be specified that the case where the insulating film is aninorganic insulating film is excluded from the invention.

As another specific example, a description of a stacked-layer structure,“a film is provided between A and B” is given. In that case, forexample, it can be specified that the case where the film is a stackedfilm of four or more layers is excluded from the invention. For example,it can be specified that the case where a conductive film is providedbetween A and the film is excluded from the invention.

Note that various people can implement the invention described in thisspecification and the like. However, different people may be involved inthe implementation of the invention. For example, in the case of atransmission reception system, the following case is possible: Company Amanufactures and sells transmitting devices, and Company B manufacturesand sells receiving devices. As another example, in the case of alight-emitting device including a TFT and a light-emitting element, thefollowing case is possible: Company A manufactures and sellssemiconductor devices including TFTs, and Company B purchases thesemiconductor devices, provides light-emitting elements for thesemiconductor devices, and completes light-emitting devices.

In such a case, one embodiment of the invention can be constituted sothat a patent infringement can be claimed against each of Company A andCompany B. That is, one embodiment of the invention with which a patentinfringement suit can be filed against Company A or Company B is clearand can be regarded as being disclosed in this specification or thelike. For example, in the case of a transmission/reception system, oneembodiment of the invention can be constituted by only a transmittingdevice and one embodiment of the invention can be constituted by only areceiving device. Those embodiments of the invention are clear and canbe regarded as being disclosed in this specification or the like. Asanother example, in the case of a light-emitting device including a TFTand a light-emitting element, one embodiment of the invention can beconstituted by only a semiconductor device including a TFT, and oneembodiment of the invention can be constituted by only a light-emittingdevice including a TFT and a light-emitting element. Those embodimentsof the invention are clear and can be regarded as being disclosed inthis specification or the like.

Note that in this specification and the like, it might be possible forthose skilled in the art to constitute one embodiment of the inventioneven when portions to which all the terminals of an active element(e.g., a transistor or a diode), a passive element (e.g., a capacitor ora resistor), or the like are connected are not specified. In otherwords, one embodiment of the invention can be clear even when connectionportions are not specified. Furthermore, in the case where a connectionportion is disclosed in this specification and the like, it can bedetermined that one embodiment of the invention in which a connectionportion is not specified is disclosed in this specification and thelike, in some cases. In particular, in the case where there are severalpossible portions to which a terminal can be connected, it is notnecessary to specify all the portions to which the terminal isconnected. Therefore, it might be possible to constitute one embodimentof the invention by specifying only portions to which some of terminalsof an active element (e.g., a transistor or a diode), a passive element(e.g., a capacitor or a resistor), or the like are connected.

Note that in this specification and the like, it might be possible forthose skilled in the art to specify the invention when at least theconnection portion of a circuit is specified. Alternatively, it might bepossible for those skilled in the art to specify the invention when atleast a function of a circuit is specified. In other words, when afunction of a circuit is specified, one embodiment of the presentinvention can be clear. Furthermore, it can be determined that oneembodiment of the present invention whose function is specified isdisclosed in this specification and the like. Therefore, when aconnection portion of a circuit is specified, the circuit is disclosedas one embodiment of the invention even when a function is notspecified, and one embodiment of the invention can be constituted.Alternatively, when a function of a circuit is specified, the circuit isdisclosed as one embodiment of the invention even when a connectionportion is not specified, and one embodiment of the invention can beconstituted.

Note that in this specification and the like, in a diagram or a textdescribed in one embodiment, it is possible to take out part of thediagram or the text and constitute an embodiment of the invention. Thus,in the case where a diagram or a text related to a certain portion isdescribed, the context taken out from part of the diagram or the text isalso disclosed as one embodiment of the invention, and one embodiment ofthe invention can be constituted. Thus, for example, in a diagram or atext including one or more of active elements (e.g., transistors ordiodes), wirings, passive elements (e.g., capacitors or resistors),conductive layers, insulating layers, semiconductor layers, organicmaterials, inorganic materials, components, devices, operating methods,manufacturing methods, or the like, it is possible to take out part ofthe diagram or the text and constitute one embodiment of the invention.For example, from a circuit diagram in which N circuit elements (e.g.,transistors or capacitors; N is an integer) are provided, it is possibleto constitute one embodiment of the invention by taking out M circuitelements (e.g., transistors or capacitors; M is an integer, where M<N).As another example, it is possible to constitute one embodiment of theinvention by taking out M layers (M is an integer, where M<A) from across-sectional view in which N layers (N is an integer) are provided.As another example, it is possible to constitute one embodiment of theinvention by taking out M elements (M is an integer, where M<N) from aflow chart in which N elements (N is an integer) are provided.

Note that in the case where at least one specific example is describedin a diagram or a text described in one embodiment in this specificationand the like, it will be readily appreciated by those skilled in the artthat a broader concept of the specific example can be derived.Therefore, in the diagram or the text described in one embodiment, inthe case where at least one specific example is described, a broaderconcept of the specific example is disclosed as one embodiment of theinvention, and one embodiment of the invention can be constituted.

Note that in this specification and the like, a content described in atleast a diagram (which may be part of the diagram) is disclosed as oneembodiment of the invention, and one embodiment of the invention can beconstituted. Therefore, when a certain content is described in adiagram, the content is disclosed as one embodiment of the inventioneven when the content is not described with a text, and one embodimentof the invention can be constituted. In a similar manner, part of adiagram, which is taken out from the diagram, is disclosed as oneembodiment of the invention, and one embodiment of the invention can beconstituted.

Note that size, the thickness of layers, or regions in the drawings areexaggerated for simplicity in some cases. Therefore, embodiments of thepresent invention are not limited to such a scale.

In this specification, for example, when the shape of an object isdescribed with use of a term such as “diameter”, “grain size(diameter)”. “dimension”, “size”, or “width”, the term can be regardedas the length of one side of a minimal cube where the object fits, or anequivalent circle diameter of a cross section of the object. The term“equivalent circle diameter of a cross section of the object” refers tothe diameter of a perfect circle having the same area as that of thecross section of the object.

Note that a “semiconductor” includes characteristics of an “insulator”in some cases when the conductivity is sufficiently low, for example.Further, a “semiconductor” and an “insulator” cannot be strictlydistinguished from each other in some cases because a border between the“semiconductor” and the “insulator” is not clear. Accordingly, a“semiconductor” in this specification can be called an “insulator” insome cases. Similarly, an “insulator” in this specification can becalled a “semiconductor” in some cases.

Furthermore, a “semiconductor” includes characteristics of a “conductor”in some cases when the conductivity is sufficiently high, for example.Furthermore, a “semiconductor” and a “conductor” cannot be strictlydistinguished from each other in some cases because a border between the“semiconductor” and the “conductor” is not clear. Accordingly, a“semiconductor” in this specification can be called a “conductor” insome cases. Similarly, a “conductor” in this specification can be calleda “semiconductor” in some cases.

Note that an impurity in a semiconductor film refers to, for example,elements other than the main components of a semiconductor film. Forexample, an element with a concentration of lower than 0.1 atomic % isan impurity. When an impurity is contained, carrier traps may be formedin the semiconductor film, the carrier mobility may be decreased, or thecrystallinity may be decreased, for example. In the case where thesemiconductor film is an oxide semiconductor film, examples of animpurity which changes characteristics of the semiconductor film includeGroup 1 elements, Group 2 elements, Group 14 elements, Group 15elements, and transition metals other than the main components;specifically, there are hydrogen (included in water), lithium, sodium,silicon, boron, phosphorus, carbon, and nitrogen, for example. In thecase where the semiconductor is an oxide semiconductor, oxygen vacanciesmay be formed by entry of impurities. Furthermore, when thesemiconductor film is a silicon film, examples of an impurity whichchanges the characteristics of the semiconductor film include oxygen,Group 1 elements except hydrogen, Group 2 elements, Group 13 elements,and Group 15 elements.

In this specification, excess oxygen refers to oxygen in excess of thestoichiometric composition, for example. Alternatively, excess oxygenrefers to oxygen released by heating, for example. Excess oxygen canmove inside a film or a layer. Excess oxygen moves between atoms in afilm or a layer or excess oxygen replaces oxygen that is a constituentof a film or a layer and moves like a billiard ball. An insulating filmhaving excess oxygen means an insulating film from which oxygen isreleased by heat treatment, for example.

In this specification, a term “parallel” indicates that the angle formedbetween two straight lines is greater than or equal to −10° and lessthan or equal to 10°, and accordingly also includes the case where theangle is greater than or equal to −5° and less than or equal to 5°. Inaddition, a term “perpendicular” indicates that the angle formed betweentwo straight lines is greater than or equal to 80° and less than orequal to 100°, and accordingly includes the case where the angle isgreater than or equal to 85° and less than or equal to 95°.

In the embodiment, a conductive film may be formed using, for example, asingle layer or a stack of a conductive film containing aluminum,titanium, chromium, cobalt, nickel, copper, yttrium, zirconium,molybdenum, ruthenium, silver, tantalum, or tungsten. As alight-transmitting conductive film, for example, an oxide film such asan In—Zn—W oxide film, an In—Sn oxide film, an In—Zn oxide film, anindium oxide film, a zinc oxide film, or a tin oxide film may be used.Furthermore, a slight amount of Al, Ga, Sb, F, or the like may be addedto the above-described oxide film. Furthermore, a metal thin film havinga thickness which enables light to be transmitted (preferably,approximately greater than or equal to 5 nm and less than or equal to 30nm) can also be used. For example, an Ag film, a Mg film, or an Ag—Mgalloy film with a thickness of 5 nm may be used. For example, as a filmthat reflects visible light efficiently, a film containing lithium,aluminum, titanium, magnesium, lanthanum, silver, silicon, or nickel canbe used.

As an insulating film, for example, a single layer or a stack of aninsulating film containing aluminum oxide, magnesium oxide, siliconoxide, silicon oxynitride, silicon nitride oxide, silicon nitride,gallium oxide, germanium oxide, yttrium oxide, zirconium oxide,lanthanum oxide, neodymium oxide, hafnium oxide, or tantalum oxide maybe used. Furthermore, a resin film made of a polyimide resin, an acrylicresin, an epoxy resin, a silicone resin, or the like may be used,

In this specification, the trigonal and rhombohedral crystal systems areincluded in the hexagonal crystal system.

In addition, terms such as “first”, “second”, and “third” in thisspecification are used in order to avoid confusion among components, andthe terms do not limit the components numerically. Therefore, forexample, the term “first” can be replaced with the term “second”,“third”, or the like as appropriate.

In this specification, in the case where an etching step is performedafter a photolithography process, a mask formed in the photolithographyprocess is removed.

In some cases, a transistor is additionally provided with a second gatefor applying a potential to a back channel. In such a case, todistinguish the two gates, the terminal that is generally called a gateis called a “front gate” and the other is called a “back gate” in thisspecification.

Note that a voltage refers to a difference between potentials of twopoints, and a potential refers to electrostatic energy (electricpotential energy) of a unit charge at a given point in an electrostaticfield. Note that in general, a difference between a potential of onepoint and a reference potential (the ground potential for example) ismerely called a potential or a voltage, and a potential and a voltageare used as synonymous words in many cases. Thus, in this specification,a potential may be rephrased as a voltage and a voltage may be rephrasedas a potential unless otherwise specified.

In this specification and the like, a voltage refers to a differencebetween a given potential and a reference potential (e.g., a groundpotential) in many cases. Thus, a voltage, a potential, and a potentialdifference can also be referred to as a potential, a voltage, and avoltage difference, respectively. Note that a voltage refers to adifference between potentials of two points, and a potential refers toelectrostatic energy (electric potential energy) of a unit charge at agiven point in an electrostatic field.

Note that in general, a potential and a voltage are relative values.Thus, a ground potential is not always 0 V.

A transistor is a kind of semiconductor elements and can achieveamplification of current or voltage, switching operation for controllingconduction or non-conduction, or the like. A transistor in thisspecification includes an insulated-gate field effect transistor (IGFET)and a thin film transistor (TFT).

In this specification and the like, a transistor is an element having atleast three terminals: a gate, a drain, and a source. The transistor hasa channel region between the drain (a drain terminal, a drain region, ora drain electrode) and the source (a source terminal, a source region,or a source electrode), and current can flow through the drain, thechannel region, and the source. Here, since the source and the drain ofthe transistor change depending on the structure, the operatingcondition, and the like of the transistor, it is difficult to definewhich is a source or a drain. Therefore, a portion functioning as asource or a drain is not called a source or a drain in sonic cases. Inthat case, for example, one of the source and the drain is referred toas a first terminal, a first electrode, or a first region and the otherof the source and the drain is referred to as a second terminal, asecond electrode, or a second region in some cases.

In this specification and the like, when it is explicitly described thatX and Y are connected, the case where X and Y are electricallyconnected, the case where X and Y are functionally connected, and thecase where X and Y are directly connected are included therein. Here, Xand Y each denote an object (e.g., a device, an element, a circuit, aline, an electrode, a terminal, a conductive film, a layer, or thelike). Accordingly, another element may be provided between elementshaving a connection relation illustrated in drawings and texts, withoutlimitation on a predetermined connection relation, for example, theconnection relation illustrated in the drawings and the texts.

Examples of the case where X and Y are directly connected include thecase where an element that allows an electrical connection between X andY (e.g., a switch, a transistor, a capacitor, an inductor, a resistor, adiode, a display element, a light-emitting element, and a load) is notconnected between X and Y, and the case where X and Y are connectedwithout the element that allows the electrical connection between X andY provided therebetween.

For example, in the case where X and Y are electrically connected, oneor more elements that enable electrical connection between X and Y(e.g., a switch, a transistor, a capacitor, an inductor, a resistor, adiode, a display element, a light-emitting element, or a load) can beconnected between X and Y. A switch is controlled to be on or off. Thatis, a switch is conducting or not conducting (is turned on or off) todetermine whether current flows therethrough or not. Alternatively, theswitch has a function of selecting and changing a current path. Notethat the case where X and Y are electrically connected includes the casewhere X and Y are directly connected.

For example, in the case where X and Y are functionally connected, oneor more circuits that enable functional connection between X and Y(e.g., a logic circuit such as an inverter, a NAND circuit, or a NORcircuit; a signal converter circuit such as a DA converter circuit, anAD converter circuit, or a gamma correction circuit; a. potential levelconverter circuit such as a power supply circuit (e.g., a step-upcircuit or a step-down circuit) or a level shifter circuit for changingthe potential level of a signal; a voltage source; a current source; aswitching circuit; an amplifier circuit such as a circuit that canincrease signal amplitude, the amount of current, or the like, anoperational amplifier, a differential amplifier circuit, a sourcefollower circuit, or a buffer circuit; a signal generation circuit; amemory circuit; and/or a control circuit) can be connected between X andY. Note that for example, in the case where a signal output from X istransmitted to Y even when another circuit is interposed between X andY, X and Y are functionally connected. Note that the case where X and Yare functionally connected includes the case where X and Y are directlyconnected and the case where X and Y are electrically connected.

Note that in this specification and the like, an explicit description “Xand Y are electrically connected” means that X and Y are electricallyconnected (i.e., the case where X and Y are connected with anotherelement or another circuit provided therebetween), X and Y arefunctionally connected (i.e., the case where X and Y are functionallyconnected with another circuit provided therebetween), and X and Y aredirectly connected (i.e., the case where X and Y are connected withoutanother element or another circuit provided therebetween). That is, inthis specification and the like, the explicit description “X and Y areelectrically connected” is the same as the description “X and Y areconnected”.

Note that, for example, the case where a source (or a first terminal orthe like) of a transistor is electrically connected to X through (or notthrough) Z1 and a drain (or a second terminal or the like) of thetransistor is electrically connected to Y through (or not through) Z2,or the case where a source (or a first terminal or the like) of atransistor is directly connected to one part of Z1 and another part ofZ1 is directly connected to X while a drain (or a second terminal or thelike) of the transistor is directly connected to one part of Z2 andanother part of Z2 is directly connected to Y, can be expressed by usingany of the following expressions.

The expressions include, for example, “X, Y, a source (or a firstterminal or the like) of a transistor, and a drain (or a second terminalor the like) of the transistor are electrically connected to each other,and X, the source (or the first terminal or the like) of the transistor,the drain (or the second terminal or the like) of the transistor, and Yare electrically connected to each other in this order”, “a source (or afirst terminal or the like) of a transistor is electrically connected toX, a drain (or a second terminal or the like) of the transistor iselectrically connected to Y, and X, the source (or the first terminal orthe like) of the transistor, the drain (or the second terminal or thelike) of the transistor, and Y are electrically connected to each otherin this order”, and “X is electrically connected to Y through a source(or a first terminal or the like) and a drain (or a second terminal orthe like) of a transistor, and X, the source (or the first terminal orthe like) of the transistor, the drain (or the second terminal or thelike) of the transistor, and Y are provided to be connected in thisorder”. When the connection order in a circuit configuration is definedby an expression similar to the above examples, a source (or a firstterminal or the like) and a drain (or a second terminal or the like) ofa transistor can be distinguished from each other to specify thetechnical scope.

Other examples of the expressions include, “a source (or a firstterminal or the like) of a transistor is electrically connected to Xthrough at least a first connection path, the first connection path doesnot include a second connection path, the second connection path is apath between the source (or the first terminal or the like) of thetransistor and a drain (or a second terminal or the like) of thetransistor, Z1 is on the first connection path, the drain (or the secondterminal or the like) of the transistor is electrically connected to Ythrough at least a third connection path, the third connection path doesnot include the second connection path, and Z2 is on the thirdconnection path”. It is also possible to use the expression “a source(or a first terminal or the like) of a transistor is electricallyconnected to X through Z1 on at least a first connection path, the firstconnection path does not include a second connection path, the secondconnection path includes a connection path through the transistor, adrain (or a second terminal or the like) of the transistor iselectrically connected to Y through Z2 on at least a third connectionpath, and the third connection path does not include the secondconnection path”. Still another example of the expression is “a source(or a first terminal or the like) of a transistor is electricallyconnected to X through Z1 on at least a first electrical path, the firstelectrical path does not include a second electrical path, the secondelectrical path is an electrical path from the source (or the firstterminal or the like) of the transistor to a drain (or a second terminalor the like) of the transistor, the drain (or the second terminal or thelike) of the transistor is electrically connected to Y through Z2 on atleast a third electrical path, the third electrical path does notinclude a fourth electrical path, and the fourth electrical path is anelectrical path from the drain (or the second terminal or the like) ofthe transistor to the source (or the first terminal or the like) of thetransistor”. When the connection path in a circuit configuration isdefined by an expression similar to the above examples, a source (or afirst terminal or the like) and a drain (or a second terminal or thelike) of a transistor can be distinguished from each other to specifythe technical scope.

Note that these expressions are examples and there is no limitation onthe expressions. Here, X, Y, Z1, and Z2 each denote an object (e.g., adevice, an element, a circuit, a wiring, an electrode, a terminal, aconductive film, and a layer).

Even when independent components are electrically connected to eachother in a circuit diagram, one component has functions of a pluralityof components in some cases. For example, when part of a wiring alsofunctions as an electrode, one conductive film functions as the wiringand the electrode. Thus, “electrical connection” in this specificationincludes in its category such a case where one conductive film hasfunctions of a plurality of components.

For example, in this specification and the like, when it is explicitlydescribed that Y is formed on or over X, it does not necessarily meanthat Y is formed on and in direct contact with X The descriptionincludes the case where X and Y are not in direct contact with eachother, that is, the case where another object is placed between X and Y.Here, each of X and Y corresponds to an object (e.g., a device, anelement, a circuit, a wiring, an electrode, a terminal, a conductivefilm, or a layer).

Accordingly, for example, when it is explicitly described that a layer Yis formed on (or over) a layer X, it includes both the case where thelayer Y is formed on and in direct contact with the layer X, and thecase where another layer (e.g., a layer Z) is formed on and in directcontact with the layer X and the layer Y is formed on and in directcontact with the layer Z. Note that another layer (e.g., the layer Z)may be a single layer or a plurality of layers (a stack).

Similarly, when it is explicitly described that Y is formed above X, itdoes not necessarily mean that Y is formed on and in direct contact withX, and another object may be placed between X and Y. Therefore, forexample, when it is described that a layer Y is formed above a layer X,it includes both the case where the layer Y is formed on and in directcontact with the layer X, and the case where another layer (e.g., alayer Z) is formed on and in direct contact with the layer X and thelayer Y is formed on and in direct contact with the layer Z. Note thatanother layer (e.g., the layer may be a single layer or a plurality oflayers (a stack).

Note that when it is explicitly described that Y is formed over, on, orabove X, it includes the case where Y is formed obliquely over/above X.

Note that the same can be said when it is explicitly described that Y isformed below or under X.

For example, in this specification and the like, terms for describingspatial arrangement, such as “over”, “above”, “under”, “below”,“laterally”, “right”, “left”, “obliquely”, “behind”, “front”, “inside”,“outside”, and “in” are often used for briefly showing a relationbetween an element and another element or between a feature and anotherfeature with reference to a diagram. Note that embodiments of thepresent invention are not limited thereto, and such terms for describingspatial arrangement can indicate not only the direction illustrated in adiagram but also another direction. For example, when it is explicitlydescribed that “Y is over X”, it does not necessarily mean that Y isplaced over X. Since a device in a diagram can be inverted or rotated by180°, the case where Y is placed under X can be included. Accordingly,“over” can refer to the direction described by “under” in addition tothe direction described by “over”. Note that the embodiments of thepresent invention are not limited to this, and “over” can refer to anyof the other directions described by “laterally”, “right”, “left”,“obliquely”, “behind”, “front”, “inside”, “outside”, and “in” inaddition to the directions described by “over” and “under” because thedevice in the diagram can be rotated in a variety of directions. Thatis, such terms can be construed as appropriate depending oncircumstances.

This embodiment is obtained by performing change, addition,modification, removal, application, superordinate conceptualization, orsubordinate conceptualization on part or the whole of anotherembodiment. Thus, part or the whole of this embodiment can be freelycombined with, applied to, or replaced with part or the whole of anotherembodiment.

EXPLANATION OF REFERENCE

-   10: electron gun chamber, 12: optical system, 14: sample chamber,    16: optical system, 18: camera, 20: observation chamber, 22: film    chamber, 32: fluorescent plate, 101: housing, 110: display panel,    111: display region, 112: display region, 113: display region, 114:    display region, 115: display region, 116: display region, 121: icon,    125: slide bar, 126: finger, 150: electronic device, 153 a: support    panel, 155 a: support panel, 155 b: support panel, 201: region, 202:    image sensor, 203: lighting element, 204: image for lighting, 205:    object, 206: image, 207 image, 208: icon, 209: icon, 300: touch    panel, 301: display portion, 302: pixel, 302B: sub-pixel, 302G:    sub-pixel, 302R: sub-pixel, 302 t: transistor, 303 c: capacitor, 303    g(1): scan line driver circuit, 303 g(2): imaging pixel driver    circuit, 303 s(1): image signal line driver circuit, 303 s(2):    imaging signal line driver circuit, 303 t: transistor, 308: imaging    pixel, 308 p: photoelectric conversion element, 308 t: transistor,    309: FPC, 310: substrate, 310 a: barrier film, 310 b: substrate, 310    c: adhesive layer, 311: wiring, 319: terminal, 321: insulating film,    328: partition, 329: spacer, 350R: light-emitting element, 351R:    lower electrode, 352: upper electrode, 353: layer, 353 a:    light-emitting unit, 353 b: light-emitting unit, 354: intermediate    layer, 360: sealant, 367BM: light-blocking layer, 367 p:    anti-reflective layer, 367R: coloring layer, 370: counter substrate,    370 a: barrier film, 370 b: substrate, 370 c: adhesive layer, 380B:    light-emitting module, 380G: light-emitting module, 380R:    light-emitting module, 401: battery, 402: receiving unit, 403:    communication device, 404: speaker, 405: speaker, 500: touch panel,    500B: touch panel, 501: display portion, 502R: sub-pixel, 502 t:    transistor, 503 c: capacitor, 503 g(1): scan line driver circuit,    503 t: transistor, 509: FPC, 510: substrate, 510 a: barrier film,    510 b: substrate, 510 c: adhesive layer, 511: wiring, 519: terminal,    521: insulating film, 528: partition, 550R: light-emitting element,    560: sealant, 567BM: light-blocking layer, 567 p: anti-reflective    layer, 567R: coloring layer, 570: substrate, 570 a: barrier film,    570 b: substrate, 570 c: adhesive layer, 580R: light-emitting    module. 590: substrate, 591: electrode, 592: electrode, 593:    insulating layer, 594: wiring, 595: touch sensor, 597: adhesive    layer, 598: wiring, and 599: connection layer.

This application is based on Japanese Patent Application serial no.2013-245670 filed with Japan Patent Office on Nov. 28, 2013, the entirecontents of which are hereby incorporated by reference.

1. An electronic device comprising: a housing; a first display regionover a front surface of the housing; a second display region over a rearsurface of the housing; and an image sensor and a lighting element overthe rear surface of the housing, wherein each of the first displayregion and the second display region comprises a light-emitting element,wherein the first display region is larger than the second displayregion, wherein the second display region is configured to display animage of an object obtained by the image sensor, and wherein thelighting element is configured to increase illuminance of the object. 2.The electronic device according to claim 1, wherein the first displayregion or the second display region is over a flexible display panel. 3.The electronic device according to claim 1, wherein the first displayregion or the second display region has a touch sensor function.
 4. Theelectronic device according to claim 1, wherein different images areconfigured to be displayed in the first display region and the seconddisplay region.
 5. The electronic device according to claim 1, whereinthe same image is configured to be displayed in the first display regionand the second display region.
 6. The electronic device according toclaim 1, wherein the first display region is configured to display aplurality of icons.
 7. The electronic device according to claim 1,further comprising a third display region over a side surface of thehousing, wherein the first display region, the second display region,and the third display region are continuously provided over the frontsurface, the rear surface, and the side surface of the housing,respectively.
 8. An electronic device comprising: a housing; a firstdisplay region over a front surface of the housing; a second displayregion over a rear surface of the housing; and an image sensor, alighting element, and a receiving unit over the rear surface of thehousing, wherein the receiving unit is used as an antenna for near fieldcommunication, wherein each of the first display region and the seconddisplay region comprises a light-emitting element, wherein the firstdisplay region is larger than the second display region, wherein thesecond display region is configured to display an image of an objectobtained by the image sensor, and wherein the lighting element isconfigured to increase illuminance of the object.
 9. The electronicdevice according to claim 8, wherein the first display region or thesecond display region is over a flexible display panel.
 10. Theelectronic device according to claim 8, wherein the first display regionor the second display region has a touch sensor function.
 11. Theelectronic device according to claim 8, wherein different images areconfigured to be displayed in the first display region and the seconddisplay region.
 12. The electronic device according to claim 8, whereinthe same image is configured to be displayed in the first display regionand the second display region.
 13. The electronic device according toclaim 8, wherein the first display region is configured to display aplurality of icons.
 14. The electronic device according to claim 8,further comprising a third display region over a side surface of thehousing, wherein the first display region, the second display region,and the third display region are continuously provided over the frontsurface, the rear surface, and the side surface of the housing,respectively.